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Abstract:

A storage system according to certain embodiments includes a client-side
signature repository that includes information representative of a set of
data blocks stored in primary storage. During restore operations, the
system can use the client-side signature repository to identify data
blocks located in primary storage. The system can also use the
client-side signature repository to identify multiple locations within
primary storage where instances of some of the data blocks to be restored
are located. Accordingly, during a restore operation of one client
computing device, the system can source a data block to be restored to
the client computing device from another client computing device that is
in primary storage.

Claims:

1. A method of restoring data to a first client computing device located
in a primary storage subsystem using data blocks residing in a data store
associated with a second client computing device located in the primary
storage subsystem, the method comprising: maintaining in a signature
repository data block signatures corresponding to data blocks that form
primary data, the primary data generated by one or more applications
executing on a plurality of client computing devices located within a
primary storage subsystem, the primary data for each respective client
computing device of the plurality of client computing devices stored in a
data store associated with the respective client computing device;
receiving a set of data block signatures corresponding to data blocks in
a secondary copy of data maintained in a secondary storage subsystem, the
secondary copy of corresponding to a previous version of the primary data
of a first client computing device of the plurality of client computing
devices; querying, using one or more processors, the signature repository
to identify at least a first group of data blocks corresponding to a
first group of data block signatures of the received set of data block
signatures, the first group of data blocks stored in the data store
associated with a second client computing device of the plurality of
client computing devices; retrieving at least some of the first group of
data blocks from the data store associated with the second client
computing device; and restoring the secondary copy to the data store
associated with the first client computing device using at least the data
blocks retrieved from the second client computing device.

2. The method of claim 1, wherein the signature repository further
includes, for each copy of a data block referenced by a signature in the
signature repository: an indication as to which respective client
computing device of the plurality of client computing devices stores the
data block; and location information indicating where the data block is
located in the data store of the respective client computing device.

3. The method of claim 1, wherein the signature repository further
includes, for each respective signature referenced in the signature
repository, an indication as to the number of copies of the data block
corresponding to the respective signature that are stored in the primary
storage subsystem.

4. The method of claim 1, wherein copies of at least a first data block
having a corresponding signature included signature repository reside in
data stores associated with multiple ones of the plurality of client
computing devices, and wherein the signature repository further includes
a sourcing order indicator usable to determine which of the copies of the
first data block is to be used in the restore of said secondary copy.

5. The method of claim 1, wherein the secondary copy is accessible using
an information management system that is configured to manage the
creation of the secondary copies, and wherein the primary data is
accessible by the applications executing on the client computing devices
without use of the information management system.

6. The method of claim 1, wherein the data block signatures are generated
using a hash algorithm.

7. The method of claim 1, wherein the first group of data blocks
correspond to data generated by one or more applications executing on the
second computing device.

9. The method of claim 1, wherein the data store of the plurality of
client computing devices comprises deduplicated data.

10. A storage system for restoring data to a primary storage subsystem
using data blocks residing in the primary storage subsystem, the storage
system comprising: a signature repository including one or more data
block signatures corresponding to data blocks that are generated by one
or more applications executing on a plurality of client computing devices
and that form primary data, the primary data for each respective client
computing device of the plurality of client computing devices stored in a
data store associated with the respective client computing device; and a
repository agent executing on a computing device that is separate from
the plurality of client computing devices, the repository agent
configured to: maintain the signature repository in one or more storage
devices; receive a set of data block signatures corresponding to data
blocks in a secondary copy of data maintained in a secondary storage
subsystem, the secondary copy corresponding to a previous version of the
primary data of a first client computing device of the plurality of
client computing devices; and query the signature repository to identify
at least a first group of data blocks corresponding to a first group of
data block signatures of the received set of data block signatures, the
first group of data blocks stored in the data store associated with a
second client computing device of the plurality of client computing
devices, wherein the secondary copy is restored to the data store
associated with the first client computing device using at least some of
the first group of data blocks that are retrieved from the data store
associated with the second client computing device.

11. The system of claim 10, wherein the signature repository further
includes, for each data copy of a data block referenced in the signature
repository: an indication as to which respective client computing device
of the plurality of client computing devices stores the data block; and
location information indicating where the data block is located in the
data store of the respective client computing device.

12. The system of claim 10, wherein the signature repository further
includes, for each respective signature referenced in the signature
repository, an indication as to the number of copies of the data block
corresponding to the respective signature that are stored in the primary
storage subsystem.

13. The system of claim 10, wherein copies of at least a first data block
having a corresponding signature included signature repository reside in
data stores associated with multiple ones of the plurality of client
computing devices, and wherein the signature repository further includes
a sourcing order indicator usable to determine which of the copies of the
first data block is to be used in the restore of said secondary copy.

14. The system of claim 10, wherein the secondary copy is a secondary
copy that is accessible using an information management system that is
configured to manage the creation of the secondary copies, and wherein
the primary data is accessible by the applications executing on the
client computing devices without use of the information management
system.

15. The system of claim 10, wherein the data block signatures are
generated using a hash algorithm.

16. The system of claim 10, wherein the first group of data blocks
correspond to data generated by one or more applications executing on one
or more production computing devices.

18. The system of claim 10, wherein the data stores of the plurality of
client computing devices comprise deduplicated data.

19. A computer-readable, non-transitory storage medium having one or more
computer-executable modules for maintaining a signature repository
accessible by multiple client computing devices in a data storage system,
the one or more computer-executable modules comprising: a first module in
communication with a plurality of client computing devices, the plurality
of client computing devices within a primary storage subsystem and having
one or more applications executing thereon that generate primary data
formed of a plurality of data blocks, the primary data for each
respective client computing device of the plurality of client computing
devices stored in a data store associated with the respective client
computing device, wherein the first module is configured to: maintain a
signature repository including data block signatures corresponding to the
plurality of data blocks that form the primary data, receive a set of
data block signatures corresponding to data blocks in a secondary copy of
data maintained in a secondary storage subsystem, the secondary copy
corresponding to a previous version of the primary data of a first client
computing device of the plurality of client computing devices; and query
the signature repository to identify at least a first group of data
blocks corresponding to a first group of data block signatures of the
received set of data block signatures, the first group of data blocks
stored in the data store associated with a second client computing device
of the plurality of client computing devices, wherein the secondary copy
is restored to the data store associated with the first client computing
device using at least some of the first group of data blocks that are
retrieved from the data store associated with the second client computing
device.

[0003] Businesses worldwide recognize the commercial value of their data
and seek reliable, cost-effective ways to protect the information stored
on their computer networks while minimizing impact on productivity.
Protecting information is often part of a routine process that is
performed within an organization.

[0004] A company might back up critical computing systems such as
databases, file servers, web servers, and so on as part of a daily,
weekly, or monthly maintenance schedule. The company may similarly
protect computing systems used by each of its employees, such as those
used by an accounting department, marketing department, engineering
department, and so forth.

[0005] Given the rapidly expanding volume of data under management,
companies also continue to seek innovative techniques for managing data
growth, in addition to protecting data. For instance, companies often
implement migration techniques for moving data to lower cost storage over
time and data reduction techniques such as for reducing redundant data,
pruning lower priority data, etc.

[0006] Enterprises also increasingly view their stored data as a valuable
asset. Along these lines, customers are looking for solutions that not
only protect and manage, but also leverage their data. For instance,
solutions providing data analysis capabilities, improved data
presentation and access features, and the like, are in increasing demand.

SUMMARY

[0007] In response to these challenges, one technique developed by storage
system providers is data deduplication. Deduplication typically involves
eliminating or reducing the amount of redundant data stored and
communicated within a storage system, improving storage utilization. For
example, data can be divided into units of a chosen granularity (e.g.,
files or sub-file data blocks). The sizes of the data blocks can be of
fixed or variable length. As new data enters the system, the data units
can be checked to see if they already exist in the storage system. If the
data unit already exists, instead of storing and/or communicating a
duplicate copy, the storage system stores and/or communicates a reference
to the existing data unit. Thus, deduplication can improve storage
utilization, system traffic (e.g., over a networked storage system), or
both.

[0008] Even in those systems employing deduplication, data management
operations, including backup and restore operations, can place heavy
demands on available network bandwidth and available system resources.
Such operations can also introduce significant delay due to communication
latency between secondary storage (e.g., non-production, backup storage)
and primary storage (e.g., production storage).

[0009] In accordance with certain aspects of the disclosure, one technique
developed to address these challenges incorporates the use of a
client-side signature repository with a store of information including a
set of signatures that correspond to data blocks stored in primary
storage, where the primary data is generated by applications running on a
set of client machines. For instance, the client-side signature
repository can include signatures of most, if not all, of the data blocks
stored in primary storage and a reference to where copies of the data
block are located throughout the primary storage, similar to an index in
a book. In this manner, the system can identify signatures (and
corresponding data blocks) that are unique to primary storage (e.g., not
found in secondary storage) and otherwise track the data blocks that
reside in primary storage. In some cases, the client-side signature
repository can be used to track the location of substantially all (e.g.,
greater than 95 percent or greater than 99 percent) of the data blocks in
primary storage. In yet other cases, the client-side signature repository
can be used to track a smaller subset of the data blocks in primary
storage.

[0010] The client-side signature repository can generate and/or store
signatures and certain metadata associated with the primary data. The
signature/metadata pairs are referred to as signature blocks in certain
embodiments, as will be described. During copy operations (e.g., backup,
replication, snapshot or other types of copy operations), restore
operations, or other types of storage operations, the client-side
signature repository can be queried to determine which data blocks reside
in primary storage (which may also be referred to as production storage
or as "client-side" storage) and which data blocks reside in secondary
storage (which may also be referred to as non-production storage). In
some embodiments, during a deduplicated backup or other copy operation,
the data blocks unique to primary storage are identified and sent to
secondary storage, while only signature information or other reference
data is sent to secondary storage for data blocks that are already
located in secondary storage. In certain instances, during a restore, the
data blocks unique to secondary storage are identified and retrieved from
secondary storage, while the data blocks already located in primary
storage are retrieved from primary storage.

[0011] The client-side signature repository can be used as part of a
storage system to reduce the demands on the network between one or more
production clients generating and storing primary data and
non-production, secondary storage storing secondary copy data, such as
backup storage. For example, one or more client-side repositories can
form part of the production client(s) or may share a common network
topology with the client(s), whereas the client(s) and the secondary
storage devices may be remote from one another or reside on differing
network topologies.

[0012] As just one example, the client-side signature repository and the
client may communicate over a local area network (LAN), while client and
secondary storage communicate over a wide area network (WAN). Thus, the
client-side signature repository can communicate more effectively (e.g.,
at a higher data transfer rate, more reliably, with less latency, etc.)
with the client than the backup storage devices can communicate with the
client.

[0013] In some embodiments, each production client maintains a local
client-side signature repository including signature information, such as
signature information corresponding only to the data blocks in that
production client, or in alternative embodiments, signature information
corresponding to multiple production clients. In certain embodiments, the
primary storage subsystem (also sometimes referred to herein as "primary
storage") maintains a shared client-side signature repository including
signature information that corresponds to data blocks stored across some
or all of the production clients. In this manner, a shared client-side
signature repository can be a global map to all of the data blocks in
primary storage.

[0014] Because the client-side signature repository in some embodiments
stores the signatures of all or substantially all of the data blocks
located in primary storage, the signatures and/or associated metadata can
be used to identify which data is already present in primary storage,
without having to read the actual data blocks themselves during the
identification process, thereby improving storage operation efficiency.
For instance, during a restore operation, the secondary storage subsystem
(also sometimes referred to herein as "secondary storage") can send a set
of signatures to primary storage for a data set that is to be restored to
a client machine. In response, the primary storage subsystem consults the
signature information in the client-side signature repository, without
reading the data blocks, to determine which data blocks are already
present in primary storage.

[0015] Primary storage can include one or more signature generation
components configured to generate the data block signatures stored in the
client-side signature repository. In some cases, each client maintains
its own signature generation module. For instance, each client-specific
signature generator can snoop or otherwise monitor data operations on the
corresponding client, and generate and send the signatures (and
corresponding metadata) to the client-side signature repository for
storage. Such a configuration can reduce network traffic within the
primary storage subsystem. In other cases, a shared signature generator
resides in primary storage (e.g., forms part of a central client-side
signature repository) and is configured to generate signatures for all of
the clients (or for at least a plurality of the clients).

[0016] The client-side signature repository can also be used to perform
storage operations in a collaborative fashion such that data from
multiple clients is sourced for storage operations that don't necessarily
involve those clients. For instance, during a collaborative copy
operation (e.g., a backup operation), in which the client-side signature
repository is used during a secondary copy operation associated with a
target client, the client-side signature repository can identify which of
the multiple clients contain a copy of a particular data block in the
copy data set. A sourcing policy can include criteria for determining
which of the identified clients to source data blocks from. Based on the
desired sourcing policy, the data block to be used in a storage operation
can be retrieved from any one of the clients storing the copy of the
subject data block, including the target client, or any other client.
Moreover, during a collaborative restore operation from secondary storage
to a target client, the client-side signature repository can be used to
identify non-target clients that include data blocks in the restore data
set, and to source the data blocks from those clients during the restore.
Among other benefits, collaborative sourcing can be used to reduce the
amount of relatively high latency traffic between primary and secondary
storage and to distribute storage operation processing across the client
machines in a desired fashion. Collaborative sourcing can also reduce the
down time of the target client, or otherwise distribute processing load
for deduplication operations.

[0017] In some embodiments, a method is provided for generating a backup
data set for a client computing device by using a signature repository
residing in a primary storage subsystem. The method can include for each
respective client computing device of one or more client computing
devices in a primary storage subsystem, monitoring the storage of a
plurality of files formed by data blocks generated by one or more
software applications running on the respective client computing device.
The plurality of files are stored in a data store associated with the
respective client computing device. The method can further include
maintaining, by a repository agent executing on one or more processors in
the primary storage subsystem, a repository indicating at least which
data blocks of the monitored files are stored in the primary storage
subsystem. In response to instructions to create a secondary copy in a
secondary storage subsystem of at least a subset of the plurality of
files stored in a data store associated with a first client computing
device of the one or more client computing devices, the method can
include querying the repository to identify at least a first group of
data blocks that form at least a portion of the subset of files and for
which matching data blocks are not stored in the secondary storage
subsystem, identifying the location of the first group of data blocks
within the primary storage subsystem, and retrieving the first group of
data blocks from one or more of the data stores associated with the one
or more client computing devices.

[0018] In certain embodiments, a method is provided for generating a
secondary copy data set for a client computing device by collaboratively
sourcing data to be used in the secondary copy data set from at least one
other client computing device. The method can include for each respective
client computing device of a plurality of client computing devices,
monitoring storage of a plurality of files formed by data blocks
generated by one or more software applications running on the respective
client computing device. The files are stored in a data store associated
with the respective client computing device. The method can further
include maintaining, by a signature repository agent executing on one or
more processors, a global mapping indicating which data blocks are stored
in the data stores associated with each of the plurality of client
computing devices. The separate copies of at least some of the data
blocks reside in the data stores of multiple ones of the plurality of
client computing devices. The method can further include in response to
instructions to create a secondary copy in secondary storage of at least
a subset of the plurality of files stored in the data store of a first
client computing device of the plurality of client computing devices,
querying, by the signature repository agent, the global mapping to
identify at least a first group of data blocks in the subset of the
plurality of files that are stored in the data store associated with a
second client computing device of the plurality of client computing
devices. The method can further include retrieving the first group of
data blocks from the data store associated with the second client
computing device, and retrieving at least some of the remaining data
blocks in the first portion from the data store associated with the first
client computing device.

[0019] In some embodiments, a method is provided for restoring data to a
primary storage subsystem using data blocks residing in the primary
storage subsystem. The method can include maintaining data block
signatures in a signature repository. The data block signatures
correspond to at least unique signatures of data blocks that form primary
data. The primary data is generated by one or more applications executing
on one or more of client computing devices. In addition, the primary data
for each respective client computing device of the one or more client
computing devices is stored in a data store associated with the
respective client computing device.

[0020] The method can further include receiving a set of data block
signatures corresponding to data blocks in a secondary copy of data
maintained in a secondary storage subsystem. The secondary copy
corresponding to a previous version of the primary data of a first client
computing device of the one or more client computing devices. The method
can further include comparing, by one or more processors, the received
set of data block signatures to the data block signatures in the
signature repository to determine which data blocks in the secondary copy
already reside in the primary storage subsystem, and restoring the
secondary copy to the data store associated with the first client
computing device using at least some of the data blocks in the secondary
copy that already reside in the primary storage subsystem. The remaining
data blocks in the secondary copy are retrieved from the secondary
storage subsystem.

[0021] In certain embodiments, a method is provided for restoring data to
a first client computing device located in a primary storage subsystem
using data blocks residing in a data store associated with a second
client computing device located in the primary storage subsystem. The
method can include maintaining in a signature repository data block
signatures corresponding to data blocks that form primary data. The
primary data generated by one or more applications executing on a
plurality of client computing devices is located within the primary
storage subsystem, and the primary data for each respective client
computing device of the plurality of client computing devices is stored
in a data store associated with the respective client computing device.
The method can further include receiving a set of data block signatures
corresponding to data blocks in a secondary copy of data maintained in a
secondary storage subsystem. The secondary copy of can correspond to a
previous version of the primary data of a first client computing device
of the plurality of client computing devices.

[0022] The method can further include querying, using one or more
processors, the signature repository to identify at least a first group
of data blocks corresponding to a first group of data block signatures of
the received set of data block signatures. The first group of data blocks
are stored in the data store associated with a second client computing
device of the plurality of client computing devices. The method can
further include retrieving at least some of the first group of data
blocks from the data store associated with the second client computing
device, and restoring the secondary copy to the data store associated
with the first client computing device using at least the data blocks
retrieved from the second client computing device.

[0023] In some embodiments, a method is provided for maintaining a
signature repository accessible by multiple client computing devices in a
data storage system. The method can include tracking storage of data
units corresponding to primary data generated by one or more applications
executing on a plurality of client computing devices that form a primary
storage subsystem. The primary data for each of the client computing
devices is stored in a data store associated with the respective client
computing device, and the primary storage subsystem is in communication
with a secondary storage subsystem that is separate from the primary
storage subsystem and is configured to maintain secondary copies of at
least some of the primary data. The method can further include
generating, by a signature agent executing on one or more processors in
the primary storage subsystem, signatures corresponding to the plurality
of tracked data units, and maintaining a signature repository including a
signature block for at least each unique signature of the generated
signatures. Each signature block can include the unique signature, and
one or data unit entries. Each entry can correspond to a copy of the data
unit associated with the unique signature that is stored in the primary
storage subsystem. Each entry can indicate which of the plurality of
client computing devices stores the corresponding copy of the data unit.
At least some of the signature blocks can include at least a first entry
indicating that a first client computing device of the plurality of
client computing devices stores a copy of the data unit and a second
entry indicating that a second client computing device of the plurality
of client computing devices stores a copy of the data unit.

[0024] In certain embodiments, a method is provided for sourcing data from
storage associated with a pool of computing devices during a data storage
operation associated with one of the computing devices in the pool. The
method can include obtaining signatures corresponding to data units that
form a data set associated with a data storage operation. The data set
can correspond to a version of primary data of a first computing device
in a pool of a plurality of computing devices. Each respective computing
device in the pool can store primary data generated by one or more
software applications executing on the respective computing device, and
the primary data stored in at least one storage device can be associated
with the respective computing device. The method can further include
populating, by one or more processors, a shared signature repository. The
shared signature repository can include signatures corresponding to at
least each unique data unit stored in the storage devices of the
computing devices in the pool. For each signature included in the
signature repository, an indication as to one or more of the computing
devices whose at least one storage device can include a copy of the data
unit corresponding to the signature. The method can further include
comparing the obtained signatures with the signature repository to
identify one or more of the computing devices in the pool whose
respective at least one storage devices include copies of data units in
the data set, consulting, by one or more processors, a priority policy;
and based on the priority policy, and for at least some data units in the
backup set, deciding to access copies of the at least some data units
from one or more computing devices in the pool other than the first
computing device.

[0032]FIG. 2A is a block diagram illustrative of an expanded view of an
exemplary client-side repository.

[0033]FIG. 2B is a block diagram illustrative of an expanded view of an
exemplary signature block stored within the client-side repository.

[0034]FIG. 3 is a flow diagram illustrative of one embodiment of a
routine implemented by a storage system for performing a secondary copy
operation using a client-side signature repository.

[0035]FIG. 4 is a state diagram illustrative of the interaction between
the various components of an exemplary storage system with respect to an
exemplary collaborative copy operation.

[0036]FIG. 5 is a flow diagram illustrative of one embodiment of a
routine implemented by a storage system for updating the client-side
repository with data block signatures.

[0037]FIG. 6 is state diagram illustrative of the interaction between the
various components of an exemplary storage system with respect to an
exemplary copy operation involving a client-side signature repository.

[0038] FIG. 7 is a flow diagram illustrative of one embodiment of a
routine implemented by a storage system for executing a deduplicated
collaborative copy operation using a client-side repository.

[0039]FIG. 8 is a flow diagram illustrative of one embodiment of a
routine implemented by a storage system for restoring data using a
client-side repository.

[0040]FIG. 9 is a state diagram illustrative of the interaction between
the various components of an exemplary storage system with respect to an
exemplary restore operation.

[0041]FIG. 10 is a state diagram illustrative of the interaction between
the various components of an embodiment of a storage system with respect
to an exemplary collaborative restore operation.

[0042]FIG. 11 is a flow diagram illustrative of one embodiment of a
routine implemented by a storage system for executing a collaborative
restore of data using a client-side repository.

[0043]FIG. 12 is a flow diagram illustrative of one embodiment of a
routine implemented by a storage system for implementing a sourcing
policy to determine where to source data blocks for a storage operation.

[0044]FIG. 13 is a block diagram illustrative of an expanded view of an
exemplary copy data set index stored within secondary storage.

[0045]FIG. 14 is a flow diagram illustrative of another embodiment of a
routine implemented by a storage system for executing a copy operation,
where information relating to when entries in a client-side signature
repository are updated is used to assist in the performance of the copy
operation.

DETAILED DESCRIPTION

[0046] Deduplication techniques designed to reduce the demands on storage
systems during backup and/or replication operations are described in
greater detail in the following U.S. patent applications, each of which
is incorporated by reference in its entirety. One or more embodiments of
the present disclosure may be used with systems and methods disclosed
therein:

[0054] In addition, one or more embodiments of the present disclosure may
also be used with systems and methods disclosed in the following patents,
each of which is hereby incorporated herein by reference in its entirety:

[0065] Systems and methods are described herein for using deduplication
and collaborative data movement techniques to improve data storage
operations. Examples of such systems and methods are discussed in further
detail herein, e.g., with respect to FIGS. 1I-14. It will be appreciated
that such techniques can be implemented by information management systems
including those that will now be described with respect to FIGS. 1A-1H.
Moreover, the componentry for implementing the deduplication and data
movement functionality shown and described with respect to FIGS. 1I-14
can be incorporated into the information management systems of FIGS.
1A-1H, where applicable.

Information Management System Overview

[0066] With the increasing importance of protecting and leveraging data,
organizations simply cannot afford to take the risk of losing critical
data. Moreover, runaway data growth and other modern realities make
protecting and managing data an increasingly difficult task. There is
therefore a need for efficient, powerful, and user-friendly solutions for
protecting and managing data.

[0067] Depending on the size of the organization, there are typically many
data production sources which are under the purview of tens, hundreds, or
even thousands of employees or other individuals. In the past, individual
employees were sometimes responsible for managing and protecting their
data. A patchwork of hardware and software point solutions have been
applied in other cases. These solutions were often provided by different
vendors and had limited or no interoperability.

[0068] Certain embodiments described herein provide systems and methods
capable of addressing these and other shortcomings of prior approaches by
implementing unified, organization-wide information management. FIG. 1A
shows one such information management system 100, which generally can
include combinations of hardware and software configured to protect and
manage data and metadata generated and used by the various computing
devices in the information management system 100.

[0069] The organization which employs the information management system
100 may be a corporation or other business entity, non-profit
organization, educational institution, household, governmental agency, or
the like.

[0070] Generally, the systems and associated components described herein
may be compatible with and/or provide some or all of the functionality of
the systems and corresponding components described in one or more of the
following U.S. patents and patent application publications assigned to
CommVault Systems, Inc., each of which is hereby incorporated in its
entirety by reference herein:

[0091] The information management system 100 can include a variety of
different computing devices. For instance, as will be described in
greater detail herein, the information management system 100 can include
one or more client computing devices 102 and secondary storage computing
devices 106.

[0092] Computing devices can include, without limitation, one or more:
workstations, personal computers, desktop computers, or other types of
generally fixed computing systems such as mainframe computers and
minicomputers.

[0093] Other computing devices can include mobile or portable computing
devices, such as one or more laptops, tablet computers, personal data
assistants, mobile phones (such as smartphones), and other mobile or
portable computing devices such as embedded computers, set top boxes,
vehicle-mounted devices, wearable computers, etc. Computing devices can
include servers, such as mail servers, file servers, database servers,
and web servers.

[0094] In some cases, a computing device includes virtualized and/or cloud
computing resources. For instance, one or more virtual machines may be
provided to the organization by a third-party cloud service vendor. Or,
in some embodiments, computing devices can include one or more virtual
machine(s) running on a physical virtual machine host operated by the
organization. As one example, the organization may use one virtual
machine as a database server and another virtual or physical machine as a
mail server. A virtual machine manager (VMM) (e.g., a Hypervisor) may
manage the virtual machines, and reside and execute on the virtual
machine host. Examples of techniques for implementing information
management techniques in a cloud computing environment are described in
U.S. Pat. No. 8,285,681, which is incorporated by reference herein.
Examples of techniques for implementing information management techniques
in a virtualized computing environment are described in U.S. Pat. No.
8,307,177, also incorporated by reference herein.

[0095] The information management system 100 can also include a variety of
storage devices, including primary storage devices 104 and secondary
storage devices 108, for example. Storage devices can generally be of any
suitable type including, without limitation, disk drives, hard-disk
arrays, semiconductor memory (e.g., solid state storage devices), network
attached storage (NAS) devices, tape libraries or other magnetic,
non-tape storage devices, optical media storage devices, combinations of
the same, and the like. In some embodiments, storage devices can form
part of a distributed file system. In some cases, storage devices are
provided in a cloud (e.g., a private cloud or one operated by a
third-party vendor). A storage device in some cases comprises a disk
array or portion thereof.

[0096] The illustrated information management system 100 includes one or
more client computing device 102 having at least one application 110
executing thereon, and one or more primary storage devices 104 storing
primary data 112. The client computing device(s) 102 and the primary
storage devices 104 may generally be referred to in some cases as a
primary storage subsystem 117.

[0097] Depending on the context, the term "information management system"
can refer to generally all of the illustrated hardware and software
components. Or, in other instances, the term may refer to only a subset
of the illustrated components.

[0098] For instance, in some cases, the information management system 100
generally refers to a combination of specialized components used to
protect, move, manage, manipulate, analyze, and/or process data and
metadata generated by the client computing devices 102. However, the
information management system 100 in some cases does not include the
underlying components that generate and/or store the primary data 112,
such as the client computing devices 102 themselves, the applications 110
and operating system residing on the client computing devices 102, and
the primary storage devices 104. As an example, "information management
system" may sometimes refer to one or more of the following components
and corresponding data structures: storage managers, data agents, and
media agents. These components will be described in further detail below.

[0099] Client Computing Devices

[0100] There are typically a variety of sources in an organization that
produce data to be protected and managed. As just one illustrative
example, in a corporate environment such data sources can be employee
workstations and company servers such as a mail server, a web server, or
the like. In the information management system 100, the data generation
sources include the one or more client computing devices 102.

[0101] The client computing devices 102 may include any of the types of
computing devices described above, without limitation, and in some cases
the client computing devices 102 are associated with one or more users
and/or corresponding user accounts, of employees or other individuals.

[0102] The information management system 100 generally addresses & handles
the data management and protection needs for the data generated by the
client computing devices 102. However, the use of this term does not
imply that the client computing devices 102 cannot be "servers" in other
respects. For instance, a particular client computing device 102 may act
as a server with respect to other devices, such as other client computing
devices 102. As just a few examples, the client computing devices 102 can
include mail servers, file servers, database servers, and web servers.

[0103] Each client computing device 102 may have one or more applications
110 (e.g., software applications) executing thereon which generate and
manipulate the data that is to be protected from loss and managed.

[0105] The client computing devices 102 can have at least one operating
system (e.g., Microsoft Windows, Mac OS X, iOS, IBM z/OS, Linux, other
Unix-based operating systems, etc.) installed thereon, which may support
or host one or more file systems and other applications 110.

[0106] As shown, the client computing devices 102 and other components in
the information management system 100 can be connected to one another via
one or more communication pathways 114. The communication pathways 114
can include one or more networks or other connection types including as
any of following, without limitation: the Internet, a wide area network
(WAN), a local area network (LAN), a Storage Area Network (SAN), a Fibre
Channel connection, a Small Computer System Interface (SCSI) connection,
a virtual private network (VPN), a token ring or TCP/IP based network, an
intranet network, a point-to-point link, a cellular network, a wireless
data transmission system, a two-way cable system, an interactive kiosk
network, a satellite network, a broadband network, a baseband network, a
neural network, other appropriate wired, wireless, or partially
wired/wireless computer or telecommunications networks, combinations of
the same or the like. The communication pathways 114 in some cases may
also include application programming interfaces (APIs) including, e.g.,
cloud service provider APIs, virtual machine management APIs, and hosted
service provider APIs.

Primary Data and Exemplary Primary Storage Devices

[0107] Primary data 112 according to some embodiments is production data
or other "live" data generated by the operating system and other
applications 110 residing on a client computing device 102. The primary
data 112 is generally stored on the primary storage device(s) 104 and is
organized via a file system supported by the client computing device 102.
For instance, the client computing device(s) 102 and corresponding
applications 110 may create, access, modify, write, delete, and otherwise
use primary data 112. In some cases, some or all of the primary data 112
can be stored in cloud storage resources.

[0108] Primary data 112 is generally in the native format of the source
application 110. According to certain aspects, primary data 112 is an
initial or first (e.g., created before any other copies or before at
least one other copy) stored copy of data generated by the source
application 110. Primary data 112 in some cases is created substantially
directly from data generated by the corresponding source applications
110.

[0109] The primary data 112 may sometimes be referred to as a "primary
copy" in the sense that it is a discrete set of data. However, the use of
this term does not necessarily imply that the "primary copy" is a copy in
the sense that it was copied or otherwise derived from another stored
version.

[0110] The primary storage devices 104 storing the primary data 112 may be
relatively fast and/or expensive (e.g., a disk drive, a hard-disk array,
solid state memory, etc.). In addition, primary data 112 may be intended
for relatively short term retention (e.g., several hours, days, or
weeks).

[0112] It can be useful in performing certain tasks to organize the
primary data 112 into units of different granularities. In general,
primary data 112 can include files, directories, file system volumes,
data blocks, extents, or any other hierarchies or organizations of data
objects. As used herein, a "data object" can refer to both (1) any file
that is currently addressable by a file system or that was previously
addressable by the file system (e.g., an archive file) and (2) a subset
of such a file (e.g., a data block).

[0113] As will be described in further detail, it can also be useful in
performing certain functions of the information management system 100 to
access and modify metadata within the primary data 112. Metadata
generally includes information about data objects or characteristics
associated with the data objects.

[0114] Metadata can include, without limitation, one or more of the
following: the data owner (e.g., the client or user that generates the
data), the last modified time (e.g., the time of the most recent
modification of the data object), a data object name (e.g., a file name),
a data object size (e.g., a number of bytes of data), information about
the content (e.g., an indication as to the existence of a particular
search term), to/from information for email (e.g., an email sender,
recipient, etc.), creation date, file type (e.g., format or application
type), last accessed time, application type (e.g., type of application
that generated the data object), location/network (e.g., a current, past
or future location of the data object and network pathways to/from the
data object), frequency of change (e.g., a period in which the data
object is modified), business unit (e.g., a group or department that
generates, manages or is otherwise associated with the data object),
aging information (e.g., a schedule, such as a time period, in which the
data object is migrated to secondary or long term storage), boot sectors,
partition layouts, file location within a file folder directory
structure, user permissions, owners, groups, access control lists
[ACLs]), system metadata (e.g., registry information), combinations of
the same or the other similar information related to the data object.

[0115] In addition to metadata generated by or related to file systems and
operating systems, some of the applications 110 and/or other components
of the information management system 100 maintain indices of metadata for
data objects, e.g., metadata associated with individual email messages.
Thus, each data object may be associated with corresponding metadata. The
use of metadata to perform classification and other functions is
described in greater detail below.

[0116] Each of the client computing devices 102 are generally associated
with and/or in communication with one or more of the primary storage
devices 104 storing corresponding primary data 112. A client computing
device 102 may be considered to be "associated with" or in "communication
with" a primary storage device 104 if it is capable of one or more of:
routing and/or storing data to the particular primary storage device 104,
coordinating the routing and/or storing of data to the particular primary
storage device 104, retrieving data from the particular primary storage
device 104, coordinating the retrieval of data from the particular
primary storage device 104, and modifying and/or deleting data retrieved
from the particular primary storage device 104.

[0117] The primary storage devices 104 can include any of the different
types of storage devices described above, or some other kind of suitable
storage device. The primary storage devices 104 may have relatively fast
I/O times and/or are relatively expensive in comparison to the secondary
storage devices 108. For example, the information management system 100
may generally regularly access data and metadata stored on primary
storage devices 104, whereas data and metadata stored on the secondary
storage devices 108 is accessed relatively less frequently.

[0118] In some cases, each primary storage device 104 is dedicated to an
associated client computing device 102. For instance, a primary storage
device 104 in one embodiment is a local disk drive of a corresponding
client computing device 102. In other cases, one or more primary storage
devices 104 can be shared by multiple client computing devices 102, e.g.,
via a network such as in a cloud storage implementation. As one example,
a primary storage device 104 can be a disk array shared by a group of
client computing devices 102, such as one of the following types of disk
arrays: EMC Clariion, EMC Symmetrix, EMC Celerra, Dell EqualLogic, IBM
XIV, NetApp FAS, HP EVA, and HP 3PAR.

[0119] The information management system 100 may also include hosted
services (not shown), which may be hosted in some cases by an entity
other than the organization that employs the other components of the
information management system 100. For instance, the hosted services may
be provided by various online service providers to the organization. Such
service providers can provide services including social networking
services, hosted email services, or hosted productivity applications or
other hosted applications).

[0120] Hosted services may include software-as-a-service (SaaS),
platform-as-a-service (PaaS), application service providers (ASPs), cloud
services, or other mechanisms for delivering functionality via a network.
As it provides services to users, each hosted service may generate
additional data and metadata under management of the information
management system 100, e.g., as primary data 112. In some cases, the
hosted services may be accessed using one of the applications 110. As an
example, a hosted mail service may be accessed via browser running on a
client computing device 102. The hosted services may be implemented in a
variety of computing environments. In some cases, they are implemented in
an environment having a similar arrangement to the information management
system 100, where various physical and logical components are distributed
over a network.

Secondary Copies and Exemplary Secondary Storage Devices

[0121] The primary data 112 stored on the primary storage devices 104 may
be compromised in some cases, such as when an employee deliberately or
accidentally deletes or overwrites primary data 112 during their normal
course of work. Or the primary storage devices 104 can be damaged or
otherwise corrupted.

[0122] For recovery and/or regulatory compliance purposes, it is therefore
useful to generate copies of the primary data 112. Accordingly, the
information management system 100 includes one or more secondary storage
computing devices 106 and one or more secondary storage devices 108
configured to create and store one or more secondary copies 116 of the
primary data 112 and associated metadata. The secondary storage computing
devices 106 and the secondary storage devices 108 may sometimes be
referred to as a secondary storage subsystem 118.

[0069] The client
computing devices 102 access or receive primary data 112 and communicate
the data, e.g., over the communication pathways 114, for storage in the
secondary storage device(s) 108.

[0124] A secondary copy 116 can comprise a separate stored copy of
application data that is derived from one or more earlier created, stored
copies (e.g., derived from primary data 112 or another secondary copy
116). Secondary copies 116 can include point-in-time data, and may be
intended for relatively long-term retention (e.g., weeks, months or
years), before some or all of the data is moved to other storage or is
discarded.

[0125] In some cases, a secondary copy 116 is a copy of application data
created and stored subsequent to at least one other stored instance
(e.g., subsequent to corresponding primary data 112 or to another
secondary copy 116), in a different storage device than at least one
previous stored copy, and/or remotely from at least one previous stored
copy. In some other cases, secondary copies can be stored in the same
storage device as primary data 112 and/or other previously stored copies.
For example, in one embodiment a disk array capable of performing
hardware snapshots stores primary data 112 and creates and stores
hardware snapshots of the primary data 112 as secondary copies 116.
Secondary copies 116 may be stored in relatively slow and/or low cost
storage (e.g., magnetic tape). A secondary copy 116 may be stored in a
backup or archive format, or in some other format different than the
native source application format or other primary data format.

[0126] In some cases, secondary copies 116 are indexed so users can browse
and restore at another point in time. After creation of a secondary copy
116 representative of certain primary data 112, a pointer or other
location indicia (e.g., a stub) may be placed in primary data 112, or be
otherwise associated with primary data 112 to indicate the current
location on the secondary storage device(s) 108.

[0127] Since an instance of a data object or metadata in primary data 112
may change over time as it is modified by an application 110 (or hosted
service or the operating system), the information management system 100
may create and manage multiple secondary copies 116 of a particular data
object or metadata, each representing the state of the data object in
primary data 112 at a particular point in time. Moreover, since an
instance of a data object in primary data 112 may eventually be deleted
from the primary storage device 104 and the file system, the information
management system 100 may continue to manage point-in-time
representations of that data object, even though the instance in primary
data 112 no longer exists.

[0128] For virtualized computing devices the operating system and other
applications 110 of the client computing device(s) 102 may execute within
or under the management of virtualization software (e.g., a VMM), and the
primary storage device(s) 104 may comprise a virtual disk created on a
physical storage device. The information management system 100 may create
secondary copies 116 of the files or other data objects in a virtual disk
file and/or secondary copies 116 of the entire virtual disk file itself
(e.g., of an entire .vmdk file).

[0129] Secondary copies 116 may be distinguished from corresponding
primary data 112 in a variety of ways, some of which will now be
described. First, as discussed, secondary copies 116 can be stored in a
different format (e.g., backup, archive, or other non-native format) than
primary data 112. For this or other reasons, secondary copies 116 may not
be directly useable by the applications 110 of the client computing
device 102, e.g., via standard system calls or otherwise without
modification, processing, or other intervention by the information
management system 100.

[0130] Secondary copies 116 are also in some embodiments stored on a
secondary storage device 108 that is inaccessible to the applications 110
running on the client computing devices 102 (and/or hosted services).
Some secondary copies 116 may be "offline copies," in that they are not
readily available (e.g. not mounted to tape or disk). Offline copies can
include copies of data that the information management system 100 can
access without human intervention (e.g. tapes within an automated tape
library, but not yet mounted in a drive), and copies that the information
management system 100 can access only with at least some human
intervention (e.g. tapes located at an offsite storage site).

The Use of Intermediate Devices for Creating Secondary Copies

[0131] Creating secondary copies can be a challenging task. For instance,
there can be hundreds or thousands of client computing devices 102
continually generating large volumes of primary data 112 to be protected.
Also, there can be significant overhead involved in the creation of
secondary copies 116. Moreover, secondary storage devices 108 may be
special purpose components, and interacting with them can require
specialized intelligence.

[0132] In some cases, the client computing devices 102 interact directly
with the secondary storage device 108 to create the secondary copies 116.
However, in view of the factors described above, this approach can
negatively impact the ability of the client computing devices 102 to
serve the applications 110 and produce primary data 112. Further, the
client computing devices 102 may not be optimized for interaction with
the secondary storage devices 108.

[0133] Thus, in some embodiments, the information management system 100
includes one or more software and/or hardware components which generally
act as intermediaries between the client computing devices 102 and the
secondary storage devices 108. In addition to off-loading certain
responsibilities from the client computing devices 102, these
intermediate components can provide other benefits. For instance, as
discussed further below with respect to FIG. 1D, distributing some of the
work involved in creating secondary copies 116 can enhance scalability.

[0134] The intermediate components can include one or more secondary
storage computing devices 106 as shown in FIG. 1A and/or one or more
media agents, which can be software modules residing on corresponding
secondary storage computing devices 106 (or other appropriate devices).
Media agents are discussed below (e.g., with respect to FIGS. 1C-1E).

[0135] The secondary storage computing device(s) 106 can comprise any of
the computing devices described above, without limitation In some cases,
the secondary storage computing device(s) 106 include specialized
hardware and/or software componentry for interacting with the secondary
storage devices 108.

[0136] To create a secondary copy 116 involving the copying of data from
the primary storage subsystem 117 to the secondary storage subsystem 118,
the client computing device 102 in some embodiments communicates the
primary data 112 to be copied (or a processed version thereof) to the
designated secondary storage computing device 106, via the communication
pathway 114. The secondary storage computing device 106 in turn conveys
the received data (or a processed version thereof) to the secondary
storage device 108. In some such configurations, the communication
pathway 114 between the client computing device 102 and the secondary
storage computing device 106 comprises a portion of a LAN, WAN or SAN. In
other cases, at least some client computing devices 102 communicate
directly with the secondary storage devices 108 (e.g., via Fibre Channel
or SCSI connections). In some other cases, one or more secondary copies
116 are created from existing secondary copies, such as in the case of an
auxiliary copy operation, described in greater detail below.

[0138] Some or all primary data objects are associated with corresponding
metadata (e.g., "Meta1-11"), which may include file system metadata
and/or application specific metadata. Stored on the secondary storage
device(s) 108 are secondary copy data objects 134A-C which may include
copies of or otherwise represent corresponding primary data objects and
metadata.

[0139] As shown, the secondary copy data objects 134A-C can individually
represent more than one primary data object. For example, secondary copy
data object 134A represents three separate primary data objects 133C, 122
and 129C (represented as 133C', 122' and 129C', respectively). Moreover,
as indicated by the prime mark ('), a secondary copy object may store a
representation of a primary data object or metadata differently than the
original format, e.g., in a compressed, encrypted, deduplicated, or other
modified format.

Exemplary Information Management System Architecture

[0140] The information management system 100 can incorporate a variety of
different hardware and software components, which can in turn be
organized with respect to one another in many different configurations,
depending on the embodiment. There are critical design choices involved
in specifying the functional responsibilities of the components and the
role of each component in the information management system 100. For
instance, as will be discussed, such design choices can impact
performance as well as the adaptability of the information management
system 100 to data growth or other changing circumstances.

[0141]FIG. 1c shows an information management system 100 designed
according to these considerations and which includes: a central storage
or information manager 140 configured to perform certain control
functions, one or more data agents 142 executing on the client computing
device(s) 102 configured to process primary data 112, and one or more
media agents 144 executing on the one or more secondary storage computing
devices 106 for performing tasks involving the secondary storage devices
108. While distributing functionality amongst multiple computing devices
can have certain advantages, in other contexts it can be beneficial to
consolidate functionality on the same computing device. As such, in
various other embodiments, one or more of the components shown in FIG. 1c
as being implemented on separate computing devices are implemented on the
same computing device. In one configuration, a storage manager 140, one
or more data agents 142, and one or more media agents 144 are all
implemented on the same computing device. In another embodiment, one or
more data agents 142 and one or more media agents 144 are implemented on
the same computing device, while the storage manager is implemented on a
separate computing device.

[0142] Storage Manager

[0143] As noted, the number of components in the information management
system 100 and the amount of data under management can be quite large.
Managing the components and data is therefore a significant task, and a
task that can grow in an often unpredictable fashion as the quantity of
components and data scale to meet the needs of the organization.

[0144] For these and other reasons, according to certain embodiments,
responsibility for controlling the information management system 100, or
at least a significant portion of that responsibility, is allocated to
the storage manager 140.

[0145] By distributing control functionality in this manner, the storage
manager 140 can be adapted independently according to changing
circumstances. Moreover, a computing device for hosting the storage
manager 140 can be selected to best suit the functions of the storage
manager 140. These and other advantages are described in further detail
below with respect to FIG. 1D.

[0146] The storage manager 140 may be a software module or other
application. The storage manager generally initiates, performs,
coordinates and/or controls storage and other information management
operations performed by the information management system 100, e.g., to
protect and control the primary data 112 and secondary copies 116 of data
and metadata.

[0147] As shown by the dashed, arrowed lines, the storage manager 140 may
communicate with and/or control some or all elements of the information
management system 100, such as the data agents 142 and media agents 144.
Thus, in certain embodiments, control information originates from the
storage manager 140, whereas payload data and payload metadata is
generally communicated between the data agents 142 and the media agents
144 (or otherwise between the client computing device(s) 102 and the
secondary storage computing device(s) 106), e.g., at the direction of the
storage manager 140. Control information can generally include parameters
and instructions for carrying out information management operations, such
as, without limitation, instructions to perform a task associated with an
operation, timing information specifying when to initiate a task
associated with an operation, data path information specifying what
components to communicate with or access in carrying out an operation,
and the like. Payload data, on the other hand, can include the actual
data involved in the storage operation, such as content data written to a
secondary storage device 108 in a secondary copy operation. Payload
metadata can include any of the types of metadata described herein, and
may be written to a storage device along with the payload content data
(e.g., in the form of a header).

[0148] In other embodiments, some information management operations are
controlled by other components in the information management system 100
(e.g., the media agent(s) 144 or data agent(s) 142), instead of or in
combination with the storage manager 140.

[0149] According to certain embodiments, the storage manager provides one
or more of the following functions:

[0156] tracking movement of data within the information management system
100;

[0157] tracking logical associations between components in the
information management system 100;

[0158] protecting metadata associated
with the information management system 100; and

[0159] implementing
operations management functionality.

[0160] The storage manager 140 may maintain a database 146 of
management-related data and information management policies 148. The
database 146 may include a management index 150 or other data structure
that stores logical associations between components of the system, user
preferences and/or profiles (e.g., preferences regarding encryption,
compression, or deduplication of primary or secondary copy data,
preferences regarding the scheduling, type, or other aspects of primary
or secondary copy or other operations, mappings of particular information
management users or user accounts to certain computing devices or other
components, etc.), management tasks, media containerization, or other
useful data. For example, the storage manager 140 may use the index 150
to track logical associations between media agents 144 and secondary
storage devices 108 and/or movement of data from primary storage devices
104 to secondary storage devices 108. For instance, the storage manager
index 150 may store data associating a client computing device 102 with a
particular media agent 144 and/or secondary storage device 108, as
specified in a storage policy.

[0161] Administrators and other employees may be able to manually
configure and initiate certain information management operations on an
individual basis. But while this may be acceptable for some recovery
operations or other relatively less frequent tasks, it is often not
workable for implementing on-going organization-wide data protection and
management.

[0162] Thus, the information management system 100 may utilize information
management policies 148 for specifying and executing information
management operations (e.g., on an automated basis). Generally, an
information management policy 148 can include a data structure or other
information source that specifies a set of parameters (e.g., criteria and
rules) associated with storage or other information management
operations.

[0163] The storage manager database 146 may maintain the information
management policies 148 and associated data, although the information
management policies 148 can be stored in any appropriate location. For
instance, a storage policy may be stored as metadata in a media agent
database 152 or in a secondary storage device 108 (e.g., as an archive
copy) for use in restore operations or other information management
operations, depending on the embodiment. Information management policies
148 are described further below.

[0164] According to certain embodiments, the storage manager database 146
comprises a relational database (e.g., an SQL database) for tracking
metadata, such as metadata associated with secondary copy operations
(e.g., what client computing devices 102 and corresponding data were
protected). This and other metadata may additionally be stored in other
locations, such as at the secondary storage computing devices 106 or on
the secondary storage devices 108, allowing data recovery without the use
of the storage manager 140.

[0165] As shown, the storage manager 140 may include a jobs agent 156, a
user interface 158, and a management agent 154, all of which may be
implemented as interconnected software modules or application programs.

[0166] The jobs agent 156 in some embodiments initiates, controls, and/or
monitors the status of some or all storage or other information
management operations previously performed, currently being performed, or
scheduled to be performed by the information management system 100. For
instance, the jobs agent 156 may access information management policies
148 to determine when and how to initiate and control secondary copy and
other information management operations, as will be discussed further.

[0167] The user interface 158 may include information processing and
display software, such as a graphical user interface ("GUI"), an
application program interface ("API"), or other interactive interface
through which users and system processes can retrieve information about
the status of information management operations (e.g., storage
operations) or issue instructions to the information management system
100 and its constituent components.

[0168] Via the user interface 158, users may optionally issue instructions
to the components in the information management system 100 regarding
performance of storage and recovery operations. For example, a user may
modify a schedule concerning the number of pending secondary copy
operations. As another example, a user may employ the GUI to view the
status of pending storage operations or to monitor the status of certain
components in the information management system 100 (e.g., the amount of
capacity left in a storage device).

[0169] The storage manager 140 may also track information that permits it
to select, designate, or otherwise identify content indices,
deduplication databases, or similar databases or resources or data sets
within its information management "cell" (or another cell) to be searched
in response to certain queries. Such queries may be entered by the user
via interaction with the user interface 158. An information management
cell may generally include a logical and/or physical grouping of a
combination of hardware and software components associated with
performing information management operations on electronic data. For
instance, the components shown in FIG. 1c may together form an
information management cell. Multiple cells may be organized
hierarchically. With this configuration, cells may inherit properties
from hierarchically superior cells or be controlled by other cells in the
hierarchy (automatically or otherwise). Alternatively, in some
embodiments, cells may inherit or otherwise be associated with
information management policies, preferences, information management
metrics, or other properties or characteristics according to their
relative position in a hierarchy of storage operation cells. Cells may
also be delineated and/or organized hierarchically according to function,
geography, architectural considerations, or other factors useful or
desirable in performing information management operations. A first cell
may represent a geographic segment of an enterprise, such as a Chicago
office, and a second storage operation cell may represent a different
geographic segment, such as a New York office. Other cells may represent
departments within a particular office. Where delineated by function, a
first cell may perform one or more first types of information management
operations (e.g., one or more first types of secondary or other copies),
and a second cell may perform one or more second types of information
management operations (e.g., one or more second types of secondary or
other copies).

[0170] In general, the management agent 154 allows multiple information
management cells 100 to communicate with one another. For example, the
information management system 100 in some cases may be one information
management cell of a network of multiple cells adjacent to one another or
otherwise logically related in a WAN or LAN. With this arrangement, the
cells may be connected to one another through respective management
agents 154.

[0171] For instance, the management agent 154 can provide the storage
manager 140 with the ability to communicate with other components within
the information management system 100 (and/or other cells within a larger
information management system) via network protocols and application
programming interfaces ("APIs") including, e.g., HTTP, HTTPS, FTP, REST,
virtualization software APIs, cloud service provider APIs, and hosted
service provider APIs. Inter-cell communication and hierarchy is
described in greater detail in U.S. Pat. No. 7,035,880, which is
incorporated by reference herein.

[0172] Data Agents

[0173] As discussed, a variety of different types of applications 110 can
reside on a given client computing device 102, including operating
systems, database applications, e-mail applications, and virtual
machines, just to name a few. And, as part of the process of creating and
restoring secondary copies 116, the client computing devices 102 may be
tasked with processing and preparing the primary data 112 from these
various different applications 110. Moreover, the nature of the
processing/preparation can differ across clients and application types,
e.g., due to inherent structural and formatting differences between
applications 110.

[0174] The one or more data agent(s) 142 are therefore advantageously
configured in some embodiments to assist in the performance of
information management operations based on the type of data that is being
protected, at a client-specific and/or application-specific level.

[0175] The data agent 142 may be a software module or component that is
generally responsible for managing, initiating, or otherwise assisting in
the performance of information management operations. For instance, the
data agent 142 may take part in performing data storage operations such
as the copying, archiving, migrating, replicating of primary data 112
stored in the primary storage device(s) 104. The data agent 142 may
receive control information from the storage manager 140, such as
commands to transfer copies of data objects, metadata, and other payload
data to the media agents 144.

[0176] In some embodiments, a data agent 142 may be distributed between
the client computing device 102 and storage manager 140 (and any other
intermediate components) or may be deployed from a remote location or its
functions approximated by a remote process that performs some or all of
the functions of data agent 142. In addition, a data agent 142 may
perform some functions provided by a media agent 144, or may perform
other functions such as encryption and deduplication.

[0178] A file system data agent, for example, may handle data files and/or
other file system information. If a client computing device 102 has two
or more types of data, one data agent 142 may be used for each data type
to copy, archive, migrate, and restore the client computing device 102
data. For example, to backup, migrate, and restore all of the data on a
Microsoft Exchange server, the client computing device 102 may use one
Microsoft Exchange Mailbox data agent 142 to backup the Exchange
mailboxes, one Microsoft Exchange Database data agent 142 to backup the
Exchange databases, one Microsoft Exchange Public Folder data agent 142
to backup the Exchange Public Folders, and one Microsoft Windows File
System data agent 142 to backup the file system of the client computing
device 102. In such embodiments, these data agents 142 may be treated as
four separate data agents 142 even though they reside on the same client
computing device 102.

[0179] Other embodiments may employ one or more generic data agents 142
that can handle and process data from two or more different applications
110, or that can handle and process multiple data types, instead of or in
addition to using specialized data agents 142. For example, one generic
data agent 142 may be used to back up, migrate and restore Microsoft
Exchange Mailbox data and Microsoft Exchange Database data while another
generic data agent may handle Microsoft Exchange Public Folder data and
Microsoft Windows File System data.

[0180] Each data agent 142 may be configured to access data and/or
metadata stored in the primary storage device(s) 104 associated with the
data agent 142 and process the data as appropriate. For example, during a
secondary copy operation, the data agent 142 may arrange or assemble the
data and metadata into one or more files having a certain format (e.g., a
particular backup or archive format) before transferring the file(s) to a
media agent 144 or other component. The file(s) may include a list of
files or other metadata. Each data agent 142 can also assist in restoring
data or metadata to primary storage devices 104 from a secondary copy
116. For instance, the data agent 142 may operate in conjunction with the
storage manager 140 and one or more of the media agents 144 to restore
data from secondary storage device(s) 108.

[0181] Media Agents

[0182] As indicated above with respect to FIG. 1A, off-loading certain
responsibilities from the client computing devices 102 to intermediate
components such as the media agent(s) 144 can provide a number of
benefits including improved client computing device 102 operation, faster
secondary copy operation performance, and enhanced scalability. As one
specific example which will be discussed below in further detail, the
media agent 144 can act as a local cache of copied data and/or metadata
that it has stored to the secondary storage device(s) 108, providing
improved restore capabilities.

[0183] Generally speaking, a media agent 144 may be implemented as a
software module that manages, coordinates, and facilitates the
transmission of data, as directed by the storage manager 140, between a
client computing device 102 and one or more secondary storage devices
108. Whereas the storage manager 140 controls the operation of the
information management system 100, the media agent 144 generally provides
a portal to secondary storage devices 108. For instance, other components
in the system interact with the media agents 144 to gain access data
stored on the secondary storage devices 108, whether it be for the
purposes of reading, writing, modifying, or deleting data. Moreover, as
will be described further, media agents 144 can generate and store data
and metadata data that generally provides insight into the data stored on
associated secondary storage devices 108.

[0184] Media agents 144 can comprise separate nodes in the information
management system 100 (e.g., nodes that are separate from the client
computing devices 102, storage manager 140, and/or secondary storage
devices 108). In general, a node within the information management system
100 can be a logically and/or physically separate component, and in some
cases is a component that is individually addressable or otherwise
identifiable. In addition, each media agent 144 may reside on a dedicated
secondary storage computing device 106 in some cases, while in other
embodiments a plurality of media agents 144 reside on the same secondary
storage computing device 106.

[0185] A media agent 144 (and corresponding media agent database 152) may
be considered to be "associated with" a particular secondary storage
device 108 if that media agent 144 is capable of one or more of: routing
and/or storing data to the particular secondary storage device 108,
coordinating the routing and/or storing of data to the particular
secondary storage device 108, retrieving data from the particular
secondary storage device 108, coordinating the retrieval of data from a
particular secondary storage device 108, and modifying and/or deleting
data retrieved from the particular secondary storage device 104.

[0186] While media agent(s) 144 are generally associated with one or more
secondary storage devices 108, one or more media agents 144 in certain
embodiments are physically separate from the secondary storage devices
108. For instance, the media agents 144 may reside on secondary storage
computing devices 106 having different housings or packages than the
secondary storage devices 108. In one example, a media agent 144 resides
on a first server computer and is in communication with a secondary
storage device(s) 108 residing in a separate, rack-mounted RAID-based
system.

[0187] Where the information management system 100 includes multiple media
agents 144 (FIG. 1D), a first media agent 144 may provide failover
functionality for a second, failed media agent 144. In addition, media
agents 144 can be dynamically selected for storage operations to provide
load balancing. Failover and load balancing are described in greater
detail below.

[0188] In operation, a media agent 144 associated with a particular
secondary storage device 108 may instruct the secondary storage device
108 to perform an information management operation. For instance, a media
agent 144 may instruct a tape library to use a robotic arm or other
retrieval means to load or eject a certain storage media, and to
subsequently archive, migrate, or retrieve data to or from that media,
e.g., for the purpose of restoring the data to a client computing device
102. As another example, a secondary storage device 108 may include an
array of hard disk drives or solid state drives organized in a RAID
configuration, and the media agent 144 may forward a logical unit number
(LUN) and other appropriate information to the array, which uses the
received information to execute the desired storage operation. The media
agent 144 may communicate with a secondary storage device 108 via a
suitable communications link, such as a SCSI or Fiber Channel link.

[0189] As shown, each media agent 144 may maintain an associated media
agent database 152. The media agent database 152 may be stored in a disk
or other storage device (not shown) that is local to the secondary
storage computing device 106 on which the media agent 144 resides. In
other cases, the media agent database 152 is stored remotely from the
secondary storage computing device 106.

[0190] The media agent database 152 can include, among other things, an
index 153 including data generated during secondary copy operations and
other storage or information management operations. The index 153
provides a media agent 144 or other component with a fast and efficient
mechanism for locating secondary copies 116 or other data stored in the
secondary storage devices 108. In some cases, the index 153 does not form
a part of and is instead separate from the media agent database 152.

[0191] A media agent index 153 or other data structure associated with the
particular media agent 144 may include information about the stored data.
For instance, for each secondary copy 116, the index 153 may include
metadata such as a list of the data objects (e.g., files/subdirectories,
database objects, mailbox objects, etc.), a path to the secondary copy
116 on the corresponding secondary storage device 108, location
information indicating where the data objects are stored in the secondary
storage device 108, when the data objects were created or modified, etc.
Thus, the index 153 includes metadata associated with the secondary
copies 116 that is readily available for use in storage operations and
other activities without having to be first retrieved from the secondary
storage device 108. In yet further embodiments, some or all of the data
in the index 153 may instead or additionally be stored along with the
data in a secondary storage device 108, e.g., with a copy of the index
153. In some embodiments, the secondary storage devices 108 can include
sufficient information to perform a "bare metal restore", where the
operating system of a failed client computing device 102 or other restore
target is automatically rebuilt as part of a restore operation.

[0192] Because the index 153 maintained in the database 152 may operate as
a cache, it can also be referred to as an index cache. In such cases,
information stored in the index cache 153 typically comprises data that
reflects certain particulars about storage operations that have occurred
relatively recently. After some triggering event, such as after a certain
period of time elapses, or the index cache 153 reaches a particular size,
the index cache 153 may be copied or migrated to a secondary storage
device(s) 108. This information may need to be retrieved and uploaded
back into the index cache 153 or otherwise restored to a media agent 144
to facilitate retrieval of data from the secondary storage device(s) 108.
In some embodiments, the cached information may include format or
containerization information related to archives or other files stored on
the storage device(s) 108. In this manner, the index cache 153 allows for
accelerated restores.

[0193] In some alternative embodiments the media agent 144 generally acts
as a coordinator or facilitator of storage operations between client
computing devices 102 and corresponding secondary storage devices 108,
but does not actually write the data to the secondary storage device 108.
For instance, the storage manager 140 (or the media agent 144) may
instruct a client computing device 102 and secondary storage device 108
to communicate with one another directly. In such a case the client
computing device 102 transmits the data directly or via one or more
intermediary components to the secondary storage device 108 according to
the received instructions, and vice versa. In some such cases, the media
agent 144 may still receive, process, and/or maintain metadata related to
the storage operations. Moreover, in these embodiments, the payload data
can flow through the media agent 144 for the purposes of populating the
index cache 153 maintained in the media agent database 152, but not for
writing to the secondary storage device 108.

[0194] The media agent 144 and/or other components such as the storage
manager 140 may in some cases incorporate additional functionality, such
as data classification, content indexing, deduplication, encryption,
compression, and the like. Further details regarding these and other
functions are described below.

[0195] Distributed, Scalable Architecture

[0196] As described, certain functions of the information management
system 100 can be distributed amongst various physical and/or logical
components in the system. For instance, one or more of the storage
manager 140, data agents 142, and media agents 144 may reside on
computing devices that are physically separate from one another. This
architecture can provide a number of benefits.

[0197] For instance, hardware and software design choices for each
distributed component can be targeted to suit its particular function.
The secondary computing devices 106 on which the media agents 144 reside
can be tailored for interaction with associated secondary storage devices
108 and provide fast index cache operation, among other specific tasks.
Similarly, the client computing device(s) 102 can be selected to
effectively service the applications 110 residing thereon, in order to
efficiently produce and store primary data 112.

[0198] Moreover, in some cases, one or more of the individual components
in the information management system 100 can be distributed to multiple,
separate computing devices. As one example, for large file systems where
the amount of data stored in the storage management database 146 is
relatively large, the management database 146 may be migrated to or
otherwise reside on a specialized database server (e.g., an SQL server)
separate from a server that implements the other functions of the storage
manager 140. This configuration can provide added protection because the
database 146 can be protected with standard database utilities (e.g., SQL
log shipping or database replication) independent from other functions of
the storage manager 140. The database 146 can be efficiently replicated
to a remote site for use in the event of a disaster or other data loss
incident at the primary site. Or the database 146 can be replicated to
another computing device within the same site, such as to a higher
performance machine in the event that a storage manager host device can
no longer service the needs of a growing information management system
100.

[0199] The distributed architecture also provides both scalability and
efficient component utilization. FIG. 1D shows an embodiment of the
information management system 100 including a plurality of client
computing devices 102 and associated data agents 142 as well as a
plurality of secondary storage computing devices 106 and associated media
agents 144.

[0201] Moreover, each client computing device 102 in some embodiments can
communicate with, among other components, any of the media agents 144,
e.g., as directed by the storage manager 140. And each media agent 144
may be able to communicate with, among other components, any of the
secondary storage devices 108, e.g., as directed by the storage manager
140. Thus, operations can be routed to the secondary storage devices 108
in a dynamic and highly flexible manner, to provide load balancing,
failover, and the like. Further examples of scalable systems capable of
dynamic storage operations, and of systems capable of performing load
balancing and fail over are provided in U.S. Pat. No. 7,246,207, which is
incorporated by reference herein.

[0202] In alternative configurations, certain components are not
distributed and may instead reside and execute on the same computing
device. For example, in some embodiments one or more data agents 142 and
the storage manager 140 reside on the same client computing device 102.
In another embodiment, one or more data agents 142 and one or more media
agents 144 reside on a single computing device.

Exemplary Types of Information Management Operations

[0203] In order to protect and leverage stored data, the information
management system 100 can be configured to perform a variety of
information management operations. As will be described, these operations
can generally include secondary copy and other data movement operations,
processing and data manipulation operations, analysis, reporting, and
management operations.

[0204] Data Movement Operations

[0205] Data movement operations according to certain embodiments are
generally operations that involve the copying or migration of data (e.g.,
payload data) between different locations in the information management
system 100 in an original/native and/or one or more different formats.
For example, data movement operations can include operations in which
stored data is copied, migrated, or otherwise transferred from one or
more first storage devices to one or more second storage devices, such as
from primary storage device(s) 104 to secondary storage device(s) 108,
from secondary storage device(s) 108 to different secondary storage
device(s) 108, from secondary storage devices 108 to primary storage
devices 104, or from primary storage device(s) 104 to different primary
storage device(s) 104.

[0206] Data movement operations can include by way of example, backup
operations, archive operations, information lifecycle management
operations such as hierarchical storage management operations,
replication operations (e.g., continuous data replication operations),
snapshot operations, deduplication or single-instancing operations,
auxiliary copy operations, and the like. As will be discussed, some of
these operations involve the copying, migration or other movement of
data, without actually creating multiple, distinct copies. Nonetheless,
some or all of these operations are referred to as "copy" operations for
simplicity.

[0207] Backup Operations

[0208] A backup operation creates a copy of a version of data (e.g., one
or more files or other data units) in primary data 112 at a particular
point in time. Each subsequent backup copy may be maintained
independently of the first. Further, a backup copy in some embodiments is
generally stored in a form that is different than the native format,
e.g., a backup format. This can be in contrast to the version in primary
data 112 from which the backup copy is derived, and which may instead be
stored in a native format of the source application(s) 110. In various
cases, backup copies can be stored in a format in which the data is
compressed, encrypted, deduplicated, and/or otherwise modified from the
original application format. For example, a backup copy may be stored in
a backup format that facilitates compression and/or efficient long-term
storage.

[0209] Backup copies can have relatively long retention periods as
compared to primary data 112, and may be stored on media with slower
retrieval times than primary data 112 and certain other types of
secondary copies 116. On the other hand, backups may have relatively
shorter retention periods than some other types of secondary copies 116,
such as archive copies (described below). Backups may sometimes be stored
at on offsite location.

[0210] Backup operations can include full, synthetic or incremental
backups. A full backup in some embodiments is generally a complete image
of the data to be protected. However, because full backup copies can
consume a relatively large amount of storage, it can be useful to use a
full backup copy as a baseline and only store changes relative to the
full backup copy for subsequent backup copies.

[0211] For instance, a differential backup operation (or cumulative
incremental backup operation) tracks and stores changes that have
occurred since the last full backup. Differential backups can grow
quickly in size, but can provide relatively efficient restore times
because a restore can be completed in some cases using only the full
backup copy and the latest differential copy.

[0212] An incremental backup operation generally tracks and stores changes
since the most recent backup copy of any type, which can greatly reduce
storage utilization. In some cases, however, restore times can be
relatively long in comparison to full or differential backups because
completing a restore operation may involve accessing a full backup in
addition to multiple incremental backups.

[0213] Any of the above types of backup operations can be at the
volume-level, file-level, or block-level. Volume level backup operations
generally involve the copying of a data volume (e.g., a logical disk or
partition) as a whole. In a file-level backup, the information management
system 100 may generally track changes to individual files at the
file-level, and includes copies of files in the backup copy. In the case
of a block-level backup, files are broken into constituent blocks, and
changes are tracked at the block-level. Upon restore, the information
management system 100 reassembles the blocks into files in a transparent
fashion.

[0214] Far less data may actually be transferred and copied to the
secondary storage devices 108 during a file-level copy than a
volume-level copy. Likewise, a block-level copy may involve the transfer
of less data than a file-level copy, resulting in faster execution times.
However, restoring a relatively higher-granularity copy can result in
longer restore times. For instance, when restoring a block-level copy,
the process of locating constituent blocks can sometimes result in longer
restore times as compared to file-level backups. Similar to backup
operations, the other types of secondary copy operations described herein
can also be implemented at either the volume-level, file-level, or
block-level.

[0215] Archive Operations

[0216] Because backup operations generally involve maintaining a version
of the copied data in primary data 112 and also maintaining backup copies
in secondary storage device(s) 108, they can consume significant storage
capacity. To help reduce storage consumption, an archive operation
according to certain embodiments creates a secondary copy 116 by both
copying and removing source data. Or, seen another way, archive
operations can involve moving some or all of the source data to the
archive destination. Thus, data satisfying criteria for removal (e.g.,
data of a threshold age or size) from the source copy may be removed from
source storage. Archive copies are sometimes stored in an archive format
or other non-native application format. The source data may be primary
data 112 or a secondary copy 116, depending on the situation. As with
backup copies, archive copies can be stored in a format in which the data
is compressed, encrypted, deduplicated, and/or otherwise modified from
the original application format.

[0217] In addition, archive copies may be retained for relatively long
periods of time (e.g., years) and, in some cases, are never deleted.
Archive copies are generally retained for longer periods of time than
backup copies, for example. In certain embodiments, archive copies may be
made and kept for extended periods in order to meet compliance
regulations.

[0218] Moreover, when primary data 112 is archived, in some cases the
archived primary data 112 or a portion thereof is deleted when creating
the archive copy. Thus, archiving can serve the purpose of freeing up
space in the primary storage device(s) 104. Similarly, when a secondary
copy 116 is archived, the secondary copy 116 may be deleted, and an
archive copy can therefore serve the purpose of freeing up space in
secondary storage device(s) 108. In contrast, source copies often remain
intact when creating backup copies. Examples of compatible data archiving
operations are provided in U.S. Pat. No. 7,107,298, entitled "SYSTEM AND
METHOD FOR ARCHIVING OBJECTS IN AN INFORMATION STORE", which is
incorporated by reference herein.

[0219] Snapshot Operations

[0220] Snapshot operations can provide a relatively lightweight, efficient
mechanism for protecting data. From an end-user viewpoint, a snapshot may
be thought of as an "instant" image of the primary data 112 at a given
point in time. In one embodiment, a snapshot may generally capture the
directory structure of an object in primary data 112 such as a file or
volume or other data set at a particular moment in time and may also
preserve file attributes and contents. A snapshot in some cases is
created relatively quickly, e.g., substantially instantly, using a
minimum amount of file space, but may still function as a conventional
file system backup.

[0221] A "hardware" snapshot operation can be a snapshot operation where a
target storage device (e.g., a primary storage device 104 or a secondary
storage device 108) performs the snapshot operation in a self-contained
fashion, substantially independently, using hardware, firmware and/or
software residing on the storage device itself. For instance, the storage
device may be capable of performing snapshot operations upon request,
generally without intervention or oversight from any of the other
components in the information management system 100. In this manner,
using hardware snapshots can off-load processing involved in creating and
management from other components in the system 100.

[0222] A "software" snapshot operation, on the other hand, can be a
snapshot operation in which one or more other components in the system
(e.g., the client computing devices 102, media agents 104, etc.)
implement a software layer that manages the snapshot operation via
interaction with the target storage device. For instance, the component
implementing the snapshot management software layer may derive a set of
pointers and/or data that represents the snapshot. The snapshot
management software layer may then transmit the same to the target
storage device, along with appropriate instructions for writing the
snapshot.

[0223] Some types of snapshots do not actually create another physical
copy of all the data as it existed at the particular point in time, but
may simply create pointers that are able to map files and directories to
specific memory locations (e.g., disk blocks) where the data resides, as
it existed at the particular point in time. For example, a snapshot copy
may include a set of pointers derived from the file system or an
application. In some other cases, the snapshot may created at the
block-level, such as where creation of the snapshot occurs without
awareness of the file system. Each pointer points to a respective stored
data block, so collectively, the set of pointers reflect the storage
location and state of the data object (e.g., file(s) or volume(s) or data
set(s)) at a particular point in time when the snapshot copy was created.

[0224] In some embodiments, once a snapshot has been taken, subsequent
changes to the file system typically do not overwrite the blocks in use
at the time of the snapshot. Therefore, the initial snapshot may use only
a small amount of disk space needed to record a mapping or other data
structure representing or otherwise tracking the blocks that correspond
to the current state of the file system. Additional disk space is usually
required only when files and directories are actually modified later.
Furthermore, when files are modified, typically only the pointers which
map to blocks are copied, not the blocks themselves. In some embodiments,
for example in the case of "copy-on-write" snapshots, when a block
changes in primary storage, the block is copied to secondary storage or
cached in primary storage before the block is overwritten in primary
storage. The snapshot mapping of file system data is also updated to
reflect the changed block(s) at that particular point in time. In some
other cases, a snapshot includes a full physical copy of all or
substantially all of the data represented by the snapshot. Further
examples of snapshot operations are provided in U.S. Pat. No. 7,529,782,
which is incorporated by reference herein.

[0225] A snapshot copy in many cases can be made quickly and without
significantly impacting primary computing resources because large amounts
of data need not be copied or moved. In some embodiments, a snapshot may
exist as a virtual file system, parallel to the actual file system. Users
in some cases gain read-only access to the record of files and
directories of the snapshot. By electing to restore primary data 112 from
a snapshot taken at a given point in time, users may also return the
current file system to the state of the file system that existed when the
snapshot was taken.

[0226] Replication Operations

[0227] Another type of secondary copy operation is a replication
operation. Some types of secondary copies 116 are used to periodically
capture images of primary data 112 at particular points in time (e.g.,
backups, archives, and snapshots). However, it can also be useful for
recovery purposes to protect primary data 112 in a more continuous
fashion, by replicating the primary data 112 substantially as changes
occur. In some cases a replication copy can be a mirror copy, for
instance, where changes made to primary data 112 are mirrored or
substantially immediately copied to another location (e.g., to secondary
storage device(s) 108). By copying each write operation to the
replication copy, two storage systems are kept synchronized or
substantially synchronized so that they are virtually identical at
approximately the same time. Where entire disk volumes are mirrored,
however, mirroring can require significant amount of storage space and
utilizes a large amount of processing resources.

[0228] According to some embodiments storage operations are performed on
replicated data that represents a recoverable state, or "known good
state" of a particular application running on the source system. For
instance, in certain embodiments, known good replication copies may be
viewed as copies of primary data 112. This feature allows the system to
directly access, copy, restore, backup or otherwise manipulate the
replication copies as if the data was the "live", primary data 112. This
can reduce access time, storage utilization, and impact on source
applications 110, among other benefits.

[0229] Based on known good state information, the information management
system 100 can replicate sections of application data that represent a
recoverable state rather than rote copying of blocks of data. Examples of
compatible replication operations (e.g., continuous data replication) are
provided in U.S. Pat. No. 7,617,262, which is incorporated by reference
herein.

[0230] Deduplication/Single-Instancing Operations

[0231] Another type of data movement operation is deduplication or
single-instance storage, which is useful to reduce the amount of data
within the system. For instance, some or all of the above-described
secondary storage operations can involve deduplication in some fashion.
New data is read, broken down into portions (e.g., sub-file level blocks,
files, etc.) of a selected granularity, compared with blocks that are
already stored, and only the new blocks are stored. Blocks that already
exist are represented as pointers to the already stored data.

[0232] In order to streamline the comparison process, the information
management system 100 may calculate and/or store signatures (e.g.,
hashes) corresponding to the individual data blocks in a database and
compare the hashes instead of comparing entire data blocks. In some
cases, only a single instance of each element is stored, and
deduplication operations may therefore be referred to interchangeably as
"single-instancing" operations. Depending on the implementation, however,
deduplication or single-instancing operations can store more than one
instance of certain data blocks, but nonetheless significantly reduce
data redundancy.

[0233] Depending on the embodiment, deduplication blocks can be of fixed
or variable length. Using variable length blocks can provide enhanced
deduplication by responding to changes in the data stream, but can
involve complex processing. In some cases, the information management
system 100 utilizes a technique for dynamically aligning deduplication
blocks (e.g., fixed-length blocks) based on changing content in the data
stream, as described in U.S. Pat. Pub. No. 2012/0084269, which is
incorporated by reference herein.

[0234] The information management system 100 can perform deduplication in
a variety of manners at a variety of locations in the information
management system 100. For instance, in some embodiments, the information
management system 100 implements "target-side" deduplication by
deduplicating data (e.g., secondary copies 116) stored in the secondary
storage devices 108. In some such cases, the media agents 144 are
generally configured to manage the deduplication process. For instance,
one or more of the media agents 144 maintain a corresponding
deduplication database that stores deduplication information (e.g.,
datablock signatures). Examples of such a configuration are provided in
U.S. Pat. Pub. No. 2012/0150826, which is incorporated by reference
herein. Instead of or in combination with "target-side" deduplication,
deduplication can also be performed on the "source-side" (or
"client-side"), e.g., to reduce the amount of traffic between the media
agents 144 and the client computing device(s) 102 and/or reduce redundant
data stored in the primary storage devices 104. Examples of such
deduplication techniques are provided in U.S. Pat. Pub. No. 2012/0150818,
which is incorporated by reference herein.

[0236] In some embodiments, files and other data over their lifetime move
from more expensive, quick access storage to less expensive, slower
access storage. Operations associated with moving data through various
tiers of storage are sometimes referred to as information lifecycle
management (ILM) operations.

[0237] One type of ILM operation is a hierarchical storage management
(HSM) operation. A HSM operation is generally an operation for
automatically moving data between classes of storage devices, such as
between high-cost and low-cost storage devices. For instance, an HSM
operation may involve movement of data from primary storage devices 104
to secondary storage devices 108, or between tiers of secondary storage
devices 108. With each tier, the storage devices may be progressively
relatively cheaper, have relatively slower access/restore times, etc. For
example, movement of data between tiers may occur as data becomes less
important over time.

[0238] In some embodiments, an HSM operation is similar to an archive
operation in that creating an HSM copy may (though not always) involve
deleting some of the source data, e.g., according to one or more criteria
related to the source data. For example, an HSM copy may include data
from primary data 112 or a secondary copy 116 that is larger than a given
size threshold or older than a given age threshold and that is stored in
a backup format.

[0239] Often, and unlike some types of archive copies, HSM data that is
removed or aged from the source copy is replaced by a logical reference
pointer or stub. The reference pointer or stub can be stored in the
primary storage device 104 (or other source storage device, such as a
secondary storage device 108) to replace the deleted data in primary data
112 (or other source copy) and to point to or otherwise indicate the new
location in a secondary storage device 108.

[0240] According to one example, files are generally moved between higher
and lower cost storage depending on how often the files are accessed.
When a user requests access to the HSM data that has been removed or
migrated, the information management system 100 uses the stub to locate
the data and often make recovery of the data appear transparent, even
though the HSM data may be stored at a location different from the
remaining source data. In this manner, the data appears to the user
(e.g., in file system browsing windows and the like) as if it still
resides in the source location (e.g., in a primary storage device 104).
The stub may also include some metadata associated with the corresponding
data, so that a file system and/or application can provide some
information about the data object and/or a limited-functionality version
(e.g., a preview) of the data object.

[0241] An HSM copy may be stored in a format other than the native
application format (e.g., where the data is compressed, encrypted,
deduplicated, and/or otherwise modified from the original application
format). In some cases, copies which involve the removal of data from
source storage and the maintenance of stub or other logical reference
information on source storage may be referred to generally as "on-line
archive copies". On the other hand, copies which involve the removal of
data from source storage without the maintenance of stub or other logical
reference information on source storage may be referred to as "off-line
archive copies". Examples of HSM and ILM techniques are provided in U.S.
Pat. No. 7,343,453, which is incorporated by reference herein.

[0242] Auxiliary Copy and Disaster Recovery Operations

[0243] An auxiliary copy is generally a copy operation in which a copy is
created of an existing secondary copy 116. For instance, an initial or
"primary" secondary copy 116 may be generated using or otherwise be
derived from primary data 112 (or other data residing in the secondary
storage subsystem 118), whereas an auxiliary copy is generated from the
initial secondary copy 116. Auxiliary copies can be used to create
additional standby copies of data and may reside on different secondary
storage devices 108 than initial secondary copies 116. Thus, auxiliary
copies can be used for recovery purposes if initial secondary copies 116
become unavailable. Exemplary compatible auxiliary copy techniques are
described in further detail in U.S. Pat. No. 8,230,195, which is
incorporated by reference herein.

[0244] The information management system 100 may also perform disaster
recovery operations that make or retain disaster recovery copies, often
as secondary, high-availability disk copies. The information management
system 100 may create secondary disk copies and store the copies at
disaster recovery locations using auxiliary copy or replication
operations, such as continuous data replication technologies. Depending
on the particular data protection goals, disaster recovery locations can
be remote from the client computing devices 102 and primary storage
devices 104, remote from some or all of the secondary storage devices
108, or both.

[0245] Data Analysis, Reporting, and Management Operations

[0246] Data analysis, reporting, and management operations can be
different than data movement operations in that they do not necessarily
involve the copying, migration, or other transfer of data (e.g., primary
data 112 or secondary copies 116) between different locations in the
system. For instance, data analysis operations may involve processing
(e.g., offline processing) or modification of already stored primary data
112 and/or secondary copies 116. However, in some embodiments data
analysis operations are performed in conjunction with data movement
operations. Some data analysis operations include content indexing
operations and classification operations which can be useful in
leveraging the data under management to provide enhanced search and other
features. Other data analysis operations such as compression and
encryption can provide data reduction and security benefits,
respectively.

[0247] Classification Operations/Content Indexing

[0248] In some embodiments, the information management system 100 analyzes
and indexes characteristics, content, and metadata associated with the
data stored within the primary data 112 and/or secondary copies 116,
providing enhanced search capabilities for data discovery and other
purposes. The content indexing can be used to identify files or other
data objects having pre-defined content (e.g., user-defined keywords or
phrases), metadata (e.g., email metadata such as "to", "from", "cc",
"bcc", attachment name, received time, etc.).

[0249] The information management system 100 generally organizes and
catalogues the results in a content index, which may be stored within the
media agent database 152, for example. The content index can also include
the storage locations of (or pointer references to) the indexed data in
the primary data 112 or secondary copies 116, as appropriate. The results
may also be stored, in the form of a content index database or otherwise,
elsewhere in the information management system 100 (e.g., in the primary
storage devices 104, or in the secondary storage device 108). Such index
data provides the storage manager 140 or another component with an
efficient mechanism for locating primary data 112 and/or secondary copies
116 of data objects that match particular criteria.

[0250] For instance, search criteria can be specified by a user through
user interface 158 of the storage manager 140. In some cases, the
information management system 100 analyzes data and/or metadata in
secondary copies 116 to create an "off-line" content index, without
significantly impacting the performance of the client computing devices
102. Depending on the embodiment, the system can also implement "on-line"
content indexing, e.g., of primary data 112. Examples of compatible
content indexing techniques are provided in U.S. Pat. No. 8,170,995,
which is incorporated by reference herein.

[0251] In order to leverage the data stored in the information management
system 100 to perform these and other tasks, one or more components can
be configured to scan data and/or associated metadata for classification
purposes to populate a database of information (which can be referred to
as a "metabase"). Such scanned, classified data and/or metadata may be
included in a separate database and/or on a separate storage device from
primary data 112 (and/or secondary copies 116), such that operations
related to the database do not significantly impact performance on other
components in the information management system 100.

[0252] In other cases, the database(s) may be stored along with primary
data 112 and/or secondary copies 116. Files or other data objects can be
associated with user-specified identifiers (e.g., tag entries) in the
media agent 144 (or other indices) to facilitate searches of stored data
objects. Among a number of other benefits, the metabase can also allow
efficient, automatic identification of files or other data objects to
associate with secondary copy or other information management operations
(e.g., in lieu of scanning an entire file system). Examples of compatible
metabases and data classification operations are provided in U.S. Pat.
Nos. 8,229,954 and 7,747,579, which are incorporated by reference herein.

[0255] The information management system 100 in some cases encrypts the
data at the client level, such that the client computing devices 102
(e.g., the data agents 142) encrypt the data prior to forwarding the data
to other components, e.g., before sending the data media agents 144
during a secondary copy operation. In such cases, the client computing
device 102 may maintain or have access to an encryption key or passphrase
for decrypting the data upon restore. Encryption can also occur when
creating copies of secondary copies, e.g., when creating auxiliary copies
or archive copies. In yet further embodiments, the secondary storage
devices 108 can implement built-in, high performance hardware encryption.

[0256] Management and Reporting Operations

[0257] Certain embodiments leverage the integrated, ubiquitous nature of
the information management system 100 to provide useful system-wide
management and reporting functions. Examples of some compatible
management and reporting techniques are provided in U.S. Pat. No.
7,343,453, entitled "HIERARCHICAL SYSTEMS AND METHODS FOR PROVIDING A
UNIFIED VIEW OF STORAGE INFORMATION", which is incorporated by reference
herein.

[0259] As an example, a storage manager 140 or other component in the
information management system 100 may analyze traffic patterns and
suggest or automatically route data via a particular route to e.g.,
certain facilitate storage and minimize congestion. In some embodiments,
the system can generate predictions relating to storage operations or
storage operation information. Such predictions described may be based on
a trending analysis that may be used to predict various network
operations or use of network resources such as network traffic levels,
storage media use, use of bandwidth of communication links, use of media
agent components, etc. Further examples of traffic analysis, trend
analysis, prediction generation, and the like are described in U.S. Pat.
No. 7,343,453, which is incorporated by reference herein.

[0260] In some configurations, a master storage manager 140 may track the
status of a set of associated storage operation cells in a hierarchy of
information management cells, such as the status of jobs, system
components, system resources, and other items, by communicating with
storage managers 140 (or other components) in the respective storage
operation cells. Moreover, the master storage manager 140 may track the
status of its associated storage operation cells and associated
information management operations by receiving periodic status updates
from the storage managers 140 (or other components) in the respective
cells regarding jobs, system components, system resources, and other
items. In some embodiments, a master storage manager 140 may store status
information and other information regarding its associated storage
operation cells and other system information in its index 150 (or other
location).

[0261] The master storage manager or other component in the system may
also determine whether a storage-related criteria or other criteria is
satisfied, and perform an action or trigger event (e.g., data migration)
in response to the criteria being satisfied, such as where a storage
threshold is met for a particular volume, or where inadequate protection
exists for certain data. For instance, in some embodiments, the system
uses data from one or more storage operation cells to advise users of
risks or indicates actions that can be used to mitigate or otherwise
minimize these risks, and in some embodiments, dynamically takes action
to mitigate or minimize these risks. For example, an information
management policy may specify certain requirements (e.g., that a storage
device should maintain a certain amount of free space, that secondary
copies should occur at a particular interval, that data should be aged
and migrated to other storage after a particular period, that data on a
secondary volume should always have a certain level of availability and
be able to be restored within a given time period, that data on a
secondary volume may be mirrored or otherwise migrated to a specified
number of other volumes, etc.). If a risk condition or other criteria is
triggered, the system can notify the user of these conditions and may
suggest (or automatically implement) an action to mitigate or otherwise
address the condition or minimize risk. For example, the system may
indicate that data from a primary copy 112 should be migrated to a
secondary storage device 108 to free space on the primary storage device
104. Examples of the use of risk factors and other triggering criteria
are described in U.S. Pat. No. 7,343,453, which is incorporated by
reference herein.

[0262] In some embodiments, the system 100 may also determine whether a
metric or other indication satisfies a particular storage criteria and,
if so, perform an action. For example, as previously described, a storage
policy or other definition might indicate that a storage manager 140
should initiate a particular action if a storage metric or other
indication drops below or otherwise fails to satisfy a specified criteria
such as a threshold of data protection. Examples of such metrics are
described in U.S. Pat. No. 7,343,453, which is incorporated by reference
herein.

[0263] In some embodiments, risk factors may be quantified into certain
measurable service or risk levels for ease of comprehension. For example,
certain applications and associated data may be considered to be more
important by an enterprise than other data and services. Financial
compliance data, for example, may be of greater importance than marketing
materials, etc. Network administrators may assign priorities or "weights"
to certain data or applications, corresponding to its importance
(priority value). The level of compliance with the storage operations
specified for these applications may also be assigned a certain value.
Thus, the health, impact and overall importance of a service on an
enterprise may be determined, for example, by measuring the compliance
value and calculating the product of the priority value and the
compliance value to determine the "service level" and comparing it to
certain operational thresholds to determine if the operation is being
performed within a specified data protection service level. Further
examples of the service level determination are provided in U.S. Pat. No.
7,343,453, which is incorporated by reference herein.

[0264] The system 100 may additionally calculate data costing and data
availability associated with information management operation cells
according to an embodiment of the invention. For instance, data received
from the cell may be used in conjunction with hardware-related
information and other information about network elements to generate
indications of costs associated with storage of particular data in the
system or the availability of particular data in the system. In general,
components in the system are identified and associated information is
obtained (dynamically or manually). Characteristics or metrics associated
with the network elements may be identified and associated with that
component element for further use generating an indication of storage
cost or data availability. Exemplary information generated could include
how fast a particular department is using up available storage space, how
long data would take to recover over a particular network pathway from a
particular secondary storage device, costs over time, etc. Moreover, in
some embodiments, such information may be used to determine or predict
the overall cost associated with the storage of certain information. The
cost associated with hosting a certain application may be based, at least
in part, on the type of media on which the data resides. Storage devices
may be assigned to a particular cost category which is indicative of the
cost of storing information on that device. Further examples of costing
techniques are described in U.S. Pat. No. 7,343,453, which is
incorporated by reference herein.

[0265] Any of the above types of information (e.g., information related to
trending, predictions, job, cell or component status, risk, service
level, costing, etc.) can generally be provided to users via the user
interface 158 in a single, integrated view or console. The console may
support a reporting capability that allows for the generation of a
variety of reports, which may be tailored to a particular aspect of
information management. Report types may include: scheduling, event
management, media management and data aging. Available reports may also
include backup history, data aging history, auxiliary copy history, job
history, library and drive, media in library, restore history and storage
policy. Such reports may be specified and created at a certain point in
time as a network analysis, forecasting, or provisioning tool. Integrated
reports may also be generated that illustrate storage and performance
metrics, risks and storage costing information. Moreover, users may
create their own reports based on specific needs.

[0266] The integrated user interface 158 can include an option to show a
"virtual view" of the system that graphically depicts the various
components in the system using appropriate icons. As one example, the
user interface may provide a graphical depiction of one or more primary
storage devices 104, the secondary storage devices 108, data agents 142
and/or media agents 144, and their relationship to one another in the
information management system 100. The operations management
functionality can facilitate planning and decision-making. For example,
in some embodiments, a user may view the status of some or all jobs as
well as the status of each component of the information management system
100. Users may then plan and make decisions based on this data. For
instance, a user may view high-level information regarding storage
operations for the information management system 100, such as job status,
component status, resource status (e.g., network pathways, etc.), and
other information. The user may also drill down or use other means to
obtain more detailed information regarding a particular component, job,
or the like.

[0267] Further examples of some reporting techniques and associated
interfaces providing an integrated view of an information management
system are provided in U.S. Pat. No. 7,343,453, which is incorporated by
reference herein.

[0268] The information management system 100 can also be configured to
perform system-wide e-discovery operations in some embodiments. In
general, e-discovery operations provide a unified collection and search
capability for data in the system, such as data stored in the secondary
storage devices 108 (e.g., backups, archives, or other secondary copies
116). For example, the information management system 100 may construct
and maintain a virtual repository for data stored in the information
management system 100 that is integrated across source applications 110,
different storage device types, etc. According to some embodiments,
e-discovery utilizes other techniques described herein, such as data
classification and/or content indexing.

Information Management Policies

[0269] As indicated previously, an information management policy 148 can
include a data structure or other information source that specifies a set
of parameters (e.g., criteria and rules) associated with secondary copy
or other information management operations.

[0270] One type of information management policy 148 is a storage policy.
According to certain embodiments, a storage policy generally comprises a
data structure or other information source that defines (or includes
information sufficient to determine) a set of preferences or other
criteria for performing information management operations. Storage
policies can include one or more of the following items: (1) what data
will be associated with the storage policy; (2) a destination to which
the data will be stored; (3) datapath information specifying how the data
will be communicated to the destination; (4) the type of storage
operation to be performed; and (5) retention information specifying how
long the data will be retained at the destination.

[0271] As an illustrative example, data associated with a storage policy
can be logically organized into groups. In some cases, these logical
groupings can be referred to as "sub-clients". A sub-client may represent
static or dynamic associations of portions of a data volume. Sub-clients
may represent mutually exclusive portions. Thus, in certain embodiments,
a portion of data may be given a label and the association is stored as a
static entity in an index, database or other storage location.

[0272] Sub-clients may also be used as an effective administrative scheme
of organizing data according to data type, department within the
enterprise, storage preferences, or the like. Depending on the
configuration, sub-clients can correspond to files, folders, virtual
machines, databases, etc. In one exemplary scenario, an administrator may
find it preferable to separate e-mail data from financial data using two
different sub-clients.

[0273] A storage policy can define where data is stored by specifying a
target or destination storage device (or group of storage devices). For
instance, where the secondary storage device 108 includes a group of disk
libraries, the storage policy may specify a particular disk library for
storing the sub-clients associated with the policy. As another example,
where the secondary storage devices 108 include one or more tape
libraries, the storage policy may specify a particular tape library for
storing the sub-clients associated with the storage policy, and may also
specify a drive pool and a tape pool defining a group of tape drives and
a group of tapes, respectively, for use in storing the sub-client data.
While information in the storage policy can be statically assigned in
some cases, some or all of the information in the storage policy can also
be dynamically determined based on criteria, which can be set forth in
the storage policy. For instance, based on such criteria, a particular
destination storage device(s) (or other parameter of the storage policy)
may be determined based on characteristics associated with the data
involved in a particular storage operation, device availability (e.g.,
availability of a secondary storage device 108 or a media agent 144),
network status and conditions (e.g., identified bottlenecks), user
credentials, and the like)

[0274] Datapath information can also be included in the storage policy.
For instance, the storage policy may specify network pathways and
components to utilize when moving the data to the destination storage
device(s). In some embodiments, the storage policy specifies one or more
media agents 144 for conveying data (e.g., one or more sub-clients)
associated with the storage policy between the source (e.g., one or more
host client computing devices 102) and destination (e.g., a particular
target secondary storage device 108).

[0275] A storage policy can also specify the type(s) of operations
associated with the storage policy, such as a backup, archive, snapshot,
auxiliary copy, or the like. Retention information can specify how long
the data will be kept, depending on organizational needs (e.g., a number
of days, months, years, etc.)

[0276] The information management policies 148 may also include one or
more scheduling policies specifying when and how often to perform
operations. Scheduling information may specify with what frequency (e.g.,
hourly, weekly, daily, event-based, etc.) or under what triggering
conditions secondary copy or other information management operations will
take place. Scheduling policies in some cases are associated with
particular components, such as particular logical groupings of data
associated with a storage policy (e.g., a sub-client), client computing
device 102, and the like. In one configuration, a separate scheduling
policy is maintained for particular logical groupings of data on a client
computing device 102. The scheduling policy specifies that those logical
groupings are to be moved to secondary storage devices 108 every hour
according to storage policies associated with the respective sub-clients.

[0277] When adding a new client computing device 102, administrators can
manually configure information management policies 148 and/or other
settings, e.g., via the user interface 158. However, this can be an
involved process resulting in delays, and it may be desirable to begin
data protecting operations quickly.

[0278] Thus, in some embodiments, the information management system 100
automatically applies a default configuration to client computing device
102. As one example, when one or more data agent(s) 142 are installed on
one or more client computing devices 102, the installation script may
register the client computing device 102 with the storage manager 140,
which in turn applies the default configuration to the new client
computing device 102. In this manner, data protection operations can
begin substantially immediately. The default configuration can include a
default storage policy, for example, and can specify any appropriate
information sufficient to begin data protection operations. This can
include a type of data protection operation, scheduling information, a
target secondary storage device 108, data path information (e.g., a
particular media agent 144), and the like.

[0279] Other types of information management policies 148 are possible.
For instance, the information management policies 148 can also include
one or more audit or security policies. An audit policy is a set of
preferences, rules and/or criteria that protect sensitive data in the
information management system 100. For example, an audit policy may
define "sensitive objects" as files or objects that contain particular
keywords (e.g. "confidential," or "privileged") and/or are associated
with particular keywords (e.g., in metadata) or particular flags (e.g.,
in metadata identifying a document or email as personal, confidential,
etc.).

[0280] An audit policy may further specify rules for handling sensitive
objects. As an example, an audit policy may require that a reviewer
approve the transfer of any sensitive objects to a cloud storage site,
and that if approval is denied for a particular sensitive object, the
sensitive object should be transferred to a local storage device 104
instead. To facilitate this approval, the audit policy may further
specify how a secondary storage computing device 106 or other system
component should notify a reviewer that a sensitive object is slated for
transfer.

[0281] In some implementations, the information management policies 148
may include one or more provisioning policies. A provisioning policy can
include a set of preferences, priorities, rules, and/or criteria that
specify how clients 102 (or groups thereof) may utilize system resources,
such as available storage on cloud storage and/or network bandwidth. A
provisioning policy specifies, for example, data quotas for particular
client computing devices 102 (e.g. a number of gigabytes that can be
stored monthly, quarterly or annually). The storage manager 140 or other
components may enforce the provisioning policy. For instance, the media
agents 144 may enforce the policy when transferring data to secondary
storage devices 108. If a client computing device 102 exceeds a quota, a
budget for the client computing device 102 (or associated department) is
adjusted accordingly or an alert may trigger.

[0282] While the above types of information management policies 148 have
been described as separate policies, one or more of these can be
generally combined into a single information management policy 148. For
instance, a storage policy may also include or otherwise be associated
with one or more scheduling, audit, or provisioning policies. Moreover,
while storage policies are typically associated with moving and storing
data, other policies may be associated with other types of information
management operations. The following is a non-exhaustive list of items
the information management policies 148 may specify:

[0283] schedules
or other timing information, e.g., specifying when and/or how often to
perform information management operations;

[0287] which system components
and/or network pathways (e.g., preferred media agents 144) should be used
to perform secondary storage operations;

[0288] resource allocation
between different computing devices or other system components used in
performing information management operations (e.g., bandwidth allocation,
available storage capacity, etc.);

[0289] whether and how to synchronize
or otherwise distribute files or other data objects across multiple
computing devices or hosted services; and

[0290] retention information
specifying the length of time primary data 112 and/or secondary copies
116 should be retained, e.g., in a particular class or tier of storage
devices, or within the information management system 100.

[0291] Policies can additionally specify or depend on a variety of
historical or current criteria that may be used to determine which rules
to apply to a particular data object, system component, or information
management operation, such as:

[0292] frequency with which primary data
112 or a secondary copy 116 of a data object or metadata has been or is
predicted to be used, accessed, or modified;

[0293] time-related factors
(e.g., aging information such as time since the creation or modification
of a data object);

[0297] a
relative sensitivity (e.g., confidentiality) of a data object, e.g., as
determined by its content and/or metadata;

[0298] the current or
historical storage capacity of various storage devices;

[0299] the
current or historical network capacity of network pathways connecting
various components within the storage operation cell;

[0300] access
control lists or other security information; and

[0301] the content of a
particular data object (e.g., its textual content) or of metadata
associated with the data object.

Exemplary Storage Policy and Secondary Storage Operations

[0302] FIG. 1E shows a data flow data diagram depicting performance of
storage operations by an embodiment of an information management system
100, according to an exemplary data storage policy 148A. The information
management system 100 includes a storage manger 140, a client computing
device 102 having a file system data agent 142A and an email data agent
142B residing thereon, a primary storage device 104, two media agents
144A, 144B, and two secondary storage devices 108A, 108B: a disk library
108A and a tape library 108B. As shown, the primary storage device 104
includes primary data 112A, 1128 associated with a logical grouping of
data associated with a file system) and a logical grouping of data
associated with email data, respectively. Although for simplicity the
logical grouping of data associated with the file system is referred to
as a file system sub-client, and the logical grouping of data associated
with the email data is referred to as an email sub-client, the techniques
described with respect to FIG. 1E can be utilized in conjunction with
data that is organized in a variety of other manners.

[0303] As indicated by the dashed box, the second media agent 144B and the
tape library 108B are "off-site", and may therefore be remotely located
from the other components in the information management system 100 (e.g.,
in a different city, office building, etc.). In this manner, information
stored on the tape library 1088 may provide protection in the event of a
disaster or other failure.

[0304] The file system sub-client and its associated primary data 112A in
certain embodiments generally comprise information generated by the file
system and/or operating system of the client computing device 102, and
can include, for example, file system data (e.g., regular files, file
tables, mount points, etc.), operating system data (e.g., registries,
event logs, etc.), and the like. The e-mail sub-client, on the other
hand, and its associated primary data 112B, include data generated by an
e-mail client application operating on the client computing device 102,
and can include mailbox information, folder information, emails,
attachments, associated database information, and the like. As described
above, the sub-clients can be logical containers, and the data included
in the corresponding primary data 112A, 112B may or may not be stored
contiguously.

[0305] The exemplary storage policy 148A includes backup copy preferences
or rule set 160, disaster recovery copy preferences rule set 162, and
compliance copy preferences or rule set 164. The backup copy rule set 160
specifies that it is associated with a file system sub-client 166 and an
email sub-client 168. Each of these sub-clients 166, 168 are associated
with the particular client computing device 102. The backup copy rule set
160 further specifies that the backup operation will be written to the
disk library 108A, and designates a particular media agent 144A to convey
the data to the disk library 108A. Finally, the backup copy rule set 160
specifies that backup copies created according to the rule set 160 are
scheduled to be generated on an hourly basis and to be retained for 30
days. In some other embodiments, scheduling information is not included
in the storage policy 148A, and is instead specified by a separate
scheduling policy.

[0306] The disaster recovery copy rule set 162 is associated with the same
two sub-clients 166, 168. However, the disaster recovery copy rule set
162 is associated with the tape library 108B, unlike the backup copy rule
set 160. Moreover, the disaster recovery copy rule set 162 specifies that
a different media agent 144B than the media agent 144A associated with
the backup copy rule set 160 will be used to convey the data to the tape
library 108B. As indicated, disaster recovery copies created according to
the rule set 162 will be retained for 60 days, and will be generated on a
daily basis. Disaster recovery copies generated according to the disaster
recovery copy rule set 162 can provide protection in the event of a
disaster or other data-loss event that would affect the backup copy 116A
maintained on the disk library 108A.

[0307] The compliance copy rule set 164 is only associated with the email
sub-client 166, and not the file system sub-client 168. Compliance copies
generated according to the compliance copy rule set 164 will therefore
not include primary data 112A from the file system sub-client 166. For
instance, the organization may be under an obligation to store maintain
copies of email data for a particular period of time (e.g., 10 years) to
comply with state or federal regulations, while similar regulations do
not apply to the file system data. The compliance copy rule set 164 is
associated with the same tape library 108B and media agent 144B as the
disaster recovery copy rule set 162, although a different storage device
or media agent could be used in other embodiments. Finally, the
compliance copy rule set 164 specifies that copies generated under the
compliance copy rule set 164 will be retained for 10 years, and will be
generated on a quarterly basis.

[0308] At step 1, the storage manager 140 initiates a backup operation
according to the backup copy rule set 160. For instance, a scheduling
service running on the storage manager 140 accesses scheduling
information from the backup copy rule set 160 or a separate scheduling
policy associated with the client computing device 102, and initiates a
backup copy operation on an hourly basis. Thus, at the scheduled time
slot the storage manager 140 sends instructions to the client computing
device 102 to begin the backup operation.

[0309] At step 2, the file system data agent 142A and the email data agent
142B residing on the client computing device 102 respond to the
instructions received from the storage manager 140 by accessing and
processing the primary data 112A, 112B involved in the copy operation
from the primary storage device 104. Because the operation is a backup
copy operation, the data agent(s) 142A, 142B may format the data into a
backup format or otherwise process the data.

[0310] At step 3, the client computing device 102 communicates the
retrieved, processed data to the first media agent 144A, as directed by
the storage manager 140, according to the backup copy rule set 160. In
some other embodiments, the information management system 100 may
implement a load-balancing, availability-based, or other appropriate
algorithm to select from the available set of media agents 144A, 144B.
Regardless of the manner the media agent 144A is selected, the storage
manager 140 may further keep a record in the storage manager database 140
of the association between the selected media agent 144A and the client
computing device 102 and/or between the selected media agent 144A and the
backup copy 116A.

[0311] The target media agent 144A receives the data from the client
computing device 102, and at step 4 conveys the data to the disk library
108A to create the backup copy 116A, again at the direction of the
storage manager 140 and according to the backup copy rule set 160. The
secondary storage device 108A can be selected in other ways. For
instance, the media agent 144A may have a dedicated association with a
particular secondary storage device(s), or the storage manager 140 or
media agent 144A may select from a plurality of secondary storage
devices, e.g., according to availability, using one of the techniques
described in U.S. Pat. No. 7,246,207, which is incorporated by reference
herein.

[0312] The media agent 144A can also update its index 153 to include data
and/or metadata related to the backup copy 116A, such as information
indicating where the backup copy 116A resides on the disk library 108A,
data and metadata for cache retrieval, etc. After the 30 day retention
period expires, the storage manager 140 instructs the media agent 144A to
delete the backup copy 116A from the disk library 108A. The storage
manager 140 may similarly update its index 150 to include information
relating to the storage operation, such as information relating to the
type of storage operation, a physical location associated with one or
more copies created by the storage operation, the time the storage
operation was performed, status information relating to the storage
operation, the components involved in the storage operation, and the
like. In some cases, the storage manager 140 may update its index 150 to
include some or all of the information stored in the index 153 of the
media agent 144A.

[0313] At step 5, the storage manager 140 initiates the creation of a
disaster recovery copy 1166 according to the disaster recovery copy rule
set 162. For instance, at step 6, based on instructions received from the
storage manager 140 at step 5, the specified media agent 144B retrieves
the most recent backup copy 116A from the disk library 108A.

[0314] At step 7, again at the direction of the storage manager 140 and as
specified in the disaster recovery copy rule set 162, the media agent
144B uses the retrieved data to create a disaster recovery copy 116B on
the tape library 108B. In some cases, the disaster recovery copy 1166 is
a direct, mirror copy of the backup copy 116A, and remains in the backup
format. In other embodiments, the disaster recovery copy 116C may be
generated in some other manner, such as by using the primary data 112A,
1126 from the storage device 104 as source data. The disaster recovery
copy operation is initiated once a day and the disaster recovery copies
116A are deleted after 60 days.

[0315] At step 8, the storage manager 140 initiates the creation of a
compliance copy 116C, according to the compliance copy rule set 164. For
instance, the storage manager 140 instructs the media agent 144B to
create the compliance copy 116C on the tape library 108B at step 9, as
specified in the compliance copy rule set 164. In the example, the
compliance copy 116C is generated using the disaster recovery copy 116B.
In other embodiments, the compliance copy 116C is instead generated using
either the primary data 112B corresponding to the email sub-client or
using the backup copy 116A from the disk library 108A as source data. As
specified, in the illustrated example, compliance copies 116C are created
quarterly, and are deleted after ten years.

[0316] While not shown in FIG. 1E, at some later point in time, a restore
operation can be initiated involving one or more of the secondary copies
116A, 1166, 116C. As one example, a user may manually initiate a restore
of the backup copy 116A by interacting with the user interface 158 of the
storage manager 140. The storage manager 140 then accesses data in its
index 150 (and/or the respective storage policy 148A) associated with the
selected backup copy 116A to identify the appropriate media agent 144A
and/or secondary storage device 116A.

[0317] In other cases, a media agent may be selected for use in the
restore operation based on a load balancing algorithm, an availability
based algorithm, or other criteria. The selected media agent 144A
retrieves the data from the disk library 108A. For instance, the media
agent 144A may access its index 153 to identify a location of the backup
copy 116A on the disk library 108A, or may access location information
residing on the disk 108A itself.

[0318] When the backup copy 116A was recently created or accessed, the
media agent 144A accesses a cached version of the backup copy 116A
residing in the media agent index 153, without having to access the disk
library 108A for some or all of the data. Once it has retrieved the
backup copy 116A, the media agent 144A communicates the data to the
source client computing device 102. Upon receipt, the file system data
agent 142A and the email data agent 142B may unpackage (e.g., restore
from a backup format to the native application format) the data in the
backup copy 116A and restore the unpackaged data to the primary storage
device 104.

Exemplary Secondary Copy Formatting

[0319] The formatting and structure of secondary copies 116 can vary,
depending on the embodiment. In some cases, secondary copies 116 are
formatted as a series of logical data units or "chunks" (e.g., 512 MB, 1
GB, 2 GB, 4 GB, or 8 GB chunks). This can facilitate efficient
communication and writing to secondary storage devices 108, e.g.,
according to resource availability. For example, a single secondary copy
116 may be written on a chunk-by-chunk basis to a single secondary
storage device 108 or across multiple secondary storage devices 108. In
some cases, users can select different chunk sizes, e.g., to improve
throughput to tape storage devices.

[0320] Generally, each chunk can include a header and a payload. The
payload can include files (or other data units) or subsets thereof
included in the chunk, whereas the chunk header generally includes
metadata relating to the chunk, some or all of which may be derived from
the payload. For example, during a secondary copy operation, the media
agent 144, storage manager 140, or other component may divide the
associated files into chunks and generate headers for each chunk by
processing the constituent files.

[0321] The headers can include a variety of information such as file
identifier(s), volume(s), offset(s), or other information associated with
the payload data items, a chunk sequence number, etc. Importantly, in
addition to being stored with the secondary copy 116 on the secondary
storage device 108, the chunk headers can also be stored to the index 153
of the associated media agent(s) 144 and/or the storage manager index
150. This is useful in some cases for providing faster processing of
secondary copies 116 during restores or other operations. In some cases,
once a chunk is successfully transferred to a secondary storage device
108, the secondary storage device 108 returns an indication of receipt,
e.g., to the media agent 144 and/or storage manager 140, which may update
their respective indexes 150, 153 accordingly. During restore, chunks may
be processed (e.g., by the media agent 144) according to the information
in the chunk header to reassemble the files.

[0322] Data can also be communicated within the information management
system 100 in data channels that connect the client computing devices 102
to the secondary storage devices 108. These data channels can be referred
to as "data streams", and multiple data streams can be employed to
parallelize an information management operation, improving data transfer
rate, among providing other advantages. Example data formatting
techniques including techniques involving data streaming, chunking, and
the use of other data structures in creating copies (e.g., secondary
copies) are described in U.S. Pat. Nos. 7,315,923 and 8,156,086, and U.S.
Pat. Pub. No. 2010-0299490, each of which is incorporated by reference
herein.

[0323] FIGS. 1F and 1G are diagrams of example data streams 170 and 171,
respectively, that may be employed for performing data storage
operations. Referring to FIG. 1F, the data agent 142 forms the data
stream 170 from the data associated with a client 102 (e.g., primary data
112). The data stream 170 is composed of multiple pairs of stream header
172 and stream payload 174. The data streams 170 and 171 shown in the
illustrated example are for a single-instanced storage operation, and a
stream payload 174 therefore includes both single-instance ("SI") data
and/or non-SI data. A stream header 172 includes metadata about the
stream payload 174. This metadata may include, for example, a length of
the stream payload 174, an indication of whether the stream payload 174
is encrypted, an indication of whether the stream payload 174 is
compressed, an archive file identifier (ID), an indication of whether the
stream payload 174 is single instanceable, and an indication of whether
the stream payload 174 is a start of a block of data.

[0324] Referring to FIG. 1G, the data stream 171 has the stream header 172
and stream payload 174 aligned into multiple data blocks. In this
example, the data blocks are of size 64 Kb. The first two stream header
172 and stream payload 174 pairs comprise a first data block of size 64
Kb. The first stream header 172 indicates that the length of the
succeeding stream payload 174 is 63 Kb and that it is the start of a data
block. The next stream header 172 indicates that the succeeding stream
payload 174 has a length of 1 Kb and that it is not the start of a new
data block. Immediately following stream payload 174 are an identifier
header 176 and identifier data 178 pair. The identifier header 176
includes an indication that the succeeding identifier data 178 includes
the identifier for the immediately previous data block. The identifier
data 178 includes the identifier that the data agent 142 generated for
the data block. The data stream 171 also includes other stream header 172
and stream payload 174 pairs, which may be for SI data and/or for non-SI
data.

[0325]FIG. 1H is a diagram illustrating the data structures 180 that may
be used to store blocks of SI data and non-SI data on the storage device
(e.g., secondary storage device 108). According to certain embodiments,
the data structures 180 do not form part of a native file system of the
storage device. The data structures 180 include one or more volume
folders 182, one or more chunk folders 184/185 within a volume folder
182, and multiple files within a chunk folder 184. Each chunk folder
184/185 includes a metadata file 186/187, a metadata index file 188/189,
one or more container files 190/191/193, and a container index file
192/194. The metadata file 186/187 stores non-SI data blocks as well as
links to SI data blocks stored in container files. The metadata index
file 188/189 stores an index to the data in the metadata file 186/187.
The container files 190/191/193 store SI data blocks. The container index
file 192/194 stores an index to the container files 190/191/193. Among
other things, the container index file 192/194 stores an indication of
whether a corresponding block in a container file 190/191/193 is referred
to by a link in a metadata file 186/187. For example, data block B2 in
the container file 190 is referred to by a link in the metadata file 187
in the chunk folder 185. Accordingly, the corresponding index entry in
the container index file 192 indicates that the data block B2 in the
container file 190 is referred to. As another example, data block B1 in
the container file 191 is referred to by a link in the metadata file 187,
and so the corresponding index entry in the container index file 192
indicates that this data block is referred to.

[0326] As an example, the data structures 180 illustrated in FIG. 7 may
have been created as a result of two storage operations involving two
clients 102. For example, a first storage operation on a first client 102
could result in the creation of the first chunk folder 184, and a second
storage operation on a second client 102 could result in the creation of
the second chunk folder 185. The container files 190/191 in the first
chunk folder 184 would contain the blocks of SI data of the first client
102. If the two clients 102 have substantially similar data, the second
storage operation on the data of the second client 102 would result in
the media agent 144 storing primarily links to the data blocks of the
first client 102 that are already stored in the container files 190/191.
Accordingly, while a first storage operation may result in storing nearly
all of the data subject to the storage operation, subsequent storage
operations involving similar data may result in substantial data storage
space savings, because links to already stored data blocks can be stored
instead of additional instances of data blocks.

[0327] If the operating system of the secondary storage computing device
106 on which the media agent 144 resides supports sparse files, then when
the media agent 144 creates container files 190/191/193, it can create
them as sparse files. As previously described, a sparse file is type of
file that may include empty space (e.g., a sparse file may have real data
within it, such as at the beginning of the file and/or at the end of the
file, but may also have empty space in it that is not storing actual
data, such as a contiguous range of bytes all having a value of zero).
Having the container files 190/191/193 be sparse files allows the media
agent 144 to free up space in the container files 190/191/193 when blocks
of data in the container files 190/191/193 no longer need to be stored on
the storage devices. In some examples, the media agent 144 creates a new
container file 190/191/193 when a container file 190/191/193 either
includes 100 blocks of data or when the size of the container file 190
exceeds 50 Mb. In other examples, the media agent 144 creates a new
container file 190/191/193 when a container file 190/191/193 satisfies
other criteria (e.g., it contains from approximately 100 to approximately
1000 blocks or when its size exceeds approximately 50 Mb to 1 Gb).

[0328] In some cases, a file on which a storage operation is performed may
comprise a large number of data blocks. For example, a 100 Mb file may be
comprised in 400 data blocks of size 256 Kb. If such a file is to be
stored, its data blocks may span more than one container file, or even
more than one chunk folder. As another example, a database file of 20 Gb
may comprise over 40,000 data blocks of size 512 Kb. If such a database
file is to be stored, its data blocks will likely span multiple container
files, multiple chunk folders, and potentially multiple volume folders.
As described in detail herein, restoring such files may thus requiring
accessing multiple container files, chunk folders, and/or volume folders
to obtain the requisite data blocks.

Example Storage Systems Including Client-Side Repositories

[0329] Examples of systems and methods will now be described for using
client-side signature to improve data storage operations. While described
in some cases with respect to certain types of operations (e.g., backup
and restore operations) for the purposes of illustration, the
deduplication and collaborative data movement techniques described herein
may be equally compatible with other types of storage operations
including archive, snapshot, and replication operations, to name a few.
Descriptions of embodiments of these and other types storage operations
compatible with embodiments described are provided above.

[0330] FIG. 1I shows a block diagram illustrative of an embodiment of a
networked storage system 100. In the illustrated embodiment of FIG. 1I,
the storage system 100 can further include one or more client-side
signature repositories 121 and one or more signature generators 123.

[0331] The client-side signature repository 121 can include a data store
containing data block signatures corresponding to data blocks that form
the primary data residing in the primary storage subsystem 117, as well
as a processing module or agent, which generally maintains the data
store, and can perform functions associated therewith (e.g., signature
comparison). As shown in the illustrated embodiment of FIG. 1I, the
client-side signature repository 121 can form part of or reside on the
client 102. For instance, the data store of the client-side signature
repository 121 forms part of the primary storage device 104 of the client
102, and the agent of the client-side signature repository 121 executes
on one or more processors of the client 102.

[0332] As will be described further with respect to FIG. 1J, in certain
other embodiments, the client-side signature repository 121 can be
separate from the client(s) 102. For instance, data store of the
client-side signature repository 121 is implemented using one or more
data stores that are separate from the primary storage devices 104 of the
clients 102. Similarly, in other embodiments, the agent of the
client-side signature repository 121 can be implemented on a computing
device that is separate from the client 102. In such cases, the computing
device on which the processing module of the client-side repository 121
and/or the storage device on which the data store of the client-side
repository 121 are implemented on can communicate with the client(s) 102
via a network (e.g., a LAN). In some embodiments, each client 102
communicates with a client-side signature repository 121 that is
dedicated to that particular client 102. In certain other embodiments,
multiple clients 102 (e.g., some or all of the clients) communicate with
a common, shared client-side signature repository 121. In yet further
embodiments, each client includes a client-side signature repository 121
to track the signatures stored thereon, and the system 100 also includes
a client-side signature repository 121 that is common to multiple clients
102 (e.g., some or all of the clients).

[0333] The signature generator 123 may be a software module that is
generally responsible for generating signatures of the data blocks
residing in the primary storage subsystem 117, e.g., primary storage
devices 104 associated with the clients 102. The signatures generated by
the signature generator 123 can be used to uniquely identify the data
blocks within the client 102 or determine when two or more data blocks
are identical. The signatures can be generated using a variety of
techniques, such as a hash function, as will be described in greater
detail below with reference to FIG. 2A.

[0334]FIG. 1J illustrates a block diagram of another embodiment of a
storage system 100. Unlike the embodiment depicted in FIG. 1I, the
embodiment shown in FIG. 1J includes a client-side signature repository
121 that is common to multiple clients 102A-102C. For instance, the
client-side signature repository 121 may be implemented on a computing
device and/or storage device distinct from the one or more clients
102A-102C. For the sake of simplicity, not all of the components and
subcomponents of the system 100 are illustrated in FIG. 1J. For example,
while not shown, the system 100 of FIG. 1J may include a storage manager
140, data agent(s) 142, secondary storage computing device(s) 106, or
other components shown in FIGS. 1A-1I.

[0335] In some embodiments, the client-side signature repository 121 is in
relatively close physical proximity to the clients 102 as compared to the
secondary storage subsystem 118, and communicates with the clients 102
using a different network topology than the topology used for
communication between the components in the primary storage subsystem 117
and the components in the secondary storage subsystem 118. For example,
in an embodiment, the clients 102 communicate with the client-side
signature repository 121 over a LAN and communicate with components in
the secondary storage subsystem 118 (e.g., the media agents 144 and/or
the secondary storage devices 108) over a WAN. In certain embodiments,
communication between the clients 102 and the client-side signature
repository 121 takes place at a higher data rate and/or with lower
latency than communication between the clients 102 and the components in
the secondary storage subsystem.

[0336] Referring again to FIG. 1I, the client-side signature repository
121 can be used by the system to store signature information relating to
data blocks or primary data units of other granularity stored in the
primary storage subsystem 117. Furthermore, depending on the embodiment,
the client-side signature repository 121 can store the corresponding
signatures of all, or substantially all of the data blocks found in the
primary storage subsystem 117. For instance, where a client-side
signature repository 121 is dedicated to a particular client 102, the
client-side signature repository 121 retains signatures corresponding to
all or substantially all (e.g., at least 90 percent, at least 95 percent,
or at least 99 percent) of the data blocks in the primary storage device
104 associated with that client 102. Where the client-side signature
repository 121 is shared, the client-side signature repository 121
retains signatures corresponding to all or substantially all of the data
blocks in the data stores of all the clients 102 that share the
client-side signature repository 121. Accordingly, the client-side
signature repository 121 can function as an index or global map of the
data blocks that form the primary data. In other cases, the client-side
signature repository 121 operates as a cache, and signatures are deleted
from the client-side signature repository 121 on a first-in first-out or
other some other basis.

[0337] The system 100 can generate or update the signature information in
the client-side signature repository 121 according to any appropriate
schedule. As one example, the system 100 can generate or update the
client-side signature repository 121 each time primary data is written or
modified in a primary storage device 104 associated with a client 102.
For example, when data is written to or modified in a primary storage
device 104, the system 100 can generate a signature for the constituent
data blocks.

[0338] In some embodiments, the client-side signature repository 121
stores a single record for each unique signature. Incoming generated
signatures are compared with signatures already stored in the client-side
signature repository 121. If a signature is already located in the
client-side signature repository 121, the record for that signature is
updated with the information corresponding to the newly written or
modified data block. If the signature is not already located in the
client-side signature repository 121, a new record is generated for that
data block. Techniques for organizing the client-side signature
repository 121 are described in further detail with respect to FIGS.
2A-2B.

[0339] In some embodiments, the storage system 100 uses the client-side
signature repository 121 to minimize or otherwise reduce the amount of
data that is transmitted to secondary storage during backup or other
secondary copy operations. Some examples of secondary copy operations
that utilize client-side signature information are described herein,
e.g., with respect to FIGS. 3-7.

[0340] Additionally, in some embodiments, the system 100 improves the
efficiency of restore operations to a target client 102 by using the
client-side signature repository to determine which data blocks in a
restore data set are already located in primary storage. Further examples
of restore operations that utilize client-side signature information are
described herein, e.g., with respect to FIGS. 8-11.

Example Signature Repository

[0341]FIG. 2A is a block diagram illustrative of an expanded view of a
client-side signature repository 121 including an agent 202 and a data
store 204. Generally speaking, the agent 202 may be implemented as a
software module that communicates with the other components of the
storage system 100 (e.g., the primary storage devices 104, the storage
manager 140, the clients 102, the media agents 144, and/or secondary
storage devices 108, and conveys data to and from the signature
repository 204. Furthermore, the client-side signature repository agent
202 can perform the various processing steps described herein that are
attributed to the client-side signature repository 121. For example, the
client-side signature repository agent 202 generally maintains the
signatures and corresponding information in the data store 204, and can
also access and process the signature information in the data store 204
to determine data blocks do and do not reside in the primary storage
devices 104.

[0342] The data store 204 can be stored on one or more storage devices of
any of the types described herein (e.g., solid state memory, disk drives
or other magnetic media, or the like).

[0343] While the signature information in the data store 204 can be
organized in a variety of ways, in certain embodiments, the signature
information is arranged as a plurality of signature blocks 206 as shown
in FIG. 2A. Each signature block 206 corresponds to a unique or
substantially unique data block signature 208 and corresponding data
block.

[0344] Each signature block 206 in some embodiments includes information
relating to copies of the corresponding data blocks stored in a subset of
one or more of the clients 102. In other embodiments, each signature
blocks 206 includes information relating to all of the copies of the
corresponding data block that are stored in the primary storage subsystem
117, e.g., across all of the primary storage devices 104.

[0345] Signature blocks 206 stored in the signature repository 204 can
include various pieces of information, or metadata, corresponding to the
copies of the corresponding data block that reside in the primary storage
subsystem 117. For example, each signature block 206 can include a
signature field 208 including the data block signature, a number of
instances field 210 that identifies the number of instances or copies of
the data block that exist on a particular client (group of multiple
clients, or within the entire primary storage subsystem 117, depending on
the embodiment), a copy operation flag 212, and entries 214 each
corresponding to a different instance or copy of the data block. The
entries 214 can further include a location information field 218, an
access/priority information field 220, and an age information field 222.
These various types of information and fields will be described below in
greater detail.

[0346] Each signature block 206 can include additional or less information
as desired. Moreover, in some other embodiments the client-side signature
repository 121 can be organized differently. For instance, while the
illustrated embodiment generally groups entries for the data block
instances into a separate signature block 206 for each unique signature,
other embodiments may instead organize the entries according to some
other scheme. For instance, entries may be grouped based on the client
102 that stores the corresponding data block entries, based on the time
the data block instance was added to the primary storage subsystem 117,
or any other appropriate scheme. In some such cases, where there are
multiple copies of a particular data block stored within the primary
storage subsystem 117, the client-side signature repository 121 may
maintain multiple copies of the corresponding unique signature--one for
each copy of the corresponding data block.

[0347] Generally speaking, the data block signatures 208 are used as a
reference to identify corresponding data blocks and/or determine whether
the corresponding data blocks are already stored in the primary storage
subsystem 117. The signature in the signature field 208 can be derived by
performing a hash or other function on the corresponding data block. In
some embodiments, the signature 208 is generated by the signature
generator 123 of the client 102 (FIG. 11). However, the signature can be
generated by a variety of different components, depending on the
implementation, such as the agent 202 of the client-side signature
repository 121, the storage manager 140, the media agent 144, and/or a
module executing on a primary storage device 104. In some embodiments,
signatures 208 are derived each time data is written to or modified on a
primary storage device 104. In other cases, signatures 208, are generated
in association with a backup, restore, or other storage operation, or
based on some other appropriate schedule. In an embodiment, the SHA-512
algorithm is used (e.g., on a 64 kB or 128 kB data block) to derive the
signature 208. The resulting signature is 256 bytes, and can be used for
deduplication purposes. Hash functions other than SHA-512 can be used on
the data blocks to derive the signature, as well as other non-hash
functions. In addition, different sized signatures may be used.
Additionally, the secondary storage subsystem 118 can also include
signature information in some embodiments. For instance, signatures for
backed up, archived, or otherwise copied data blocks residing in the
secondary storage devices 108 are maintained in the secondary storage
subsystem 118 in certain embodiments.

[0348]FIG. 2B is a block diagram illustrative of an expanded view of an
example of an entry 216 of a signature block 206 from FIG. 2A. In the
illustrated example, each entry includes an instance ID field 216, a
location information field 218, an access/priority information field 220,
and an age information field 222.

[0349] The instance ID field 216 can include an identifier for a
particular instance (i.e., copy) of the data block stored in the primary
storage subsystem 117, e.g., in a primary storage device 104 associated
with a particular client or subset of clients. In some embodiments, the
instance ID field 216 includes sourcing order information.

[0350] The location information field 218 can include information
specifying the location of the data block instance in the primary storage
subsystem 117. For instance, where the signature block 206 includes
information relating to a data block for which multiple separate
instances are stored in the primary storage subsystem 117 in association
with multiple clients 102, the location information can include a client
ID indicating the client 102 where the instance of the data block is
located. Thus, the client ID field can be useful where the system
includes a shared client-side signature repository 121 that maintains
signature information for multiple clients 102. In some cases, such as
where each client 102 maintains its own client-side signature repository
121 and there is not a shared client-side signature repository 121, the
client ID field may not be included. The location information can
additionally include physical and/or logical memory address information
usable to access the instance of the data block within the primary
storage device 104 or other data store where the instance of the data
block is stored.

[0351] In addition to providing location information, each entry can
provide access and priority information in an access/priority field 220.
The access/priority information can be used to rank or prioritize the
different instances of the data block for sourcing purposes. For
instance, where multiple copies of a particular data block are stored in
the primary storage subsystem 117 (e.g., in data stores for multiple
clients 102), the access/priority information can be used by the system
100 to determine which copy of the data block to access for a storage
operation (e.g., a backup or restore operation) or other purpose. Such
techniques are described in greater detail below with reference to FIG.
12. The access/priority field 220 can include information regarding
characteristics of the data store and/or client where the copy of the
data block is located. For example, the access/priority field 220 can
include information regarding the following for the data store that
stores the copy of the data block and/or the associated client 102,
without limitation: type and age information, speed or performance
information (e.g., hardware capability information), response time, type
or version information for installed software or firmware, storage
capacity, client operating system information, processing load (e.g.,
current or average processing load), etc. Some of these types of
information can be used to determine a relative access speed for
retrieving a copy of a particular instance of a data block.

[0352] The access/priority field 220 can also include information
regarding the network associated with the data store. For example, the
access/priority field 220 can include information regarding the network
bandwidth and speed between the data store and various target clients
within the storage network. The access/priority field 220 can also
provide information regarding downtime or scheduled maintenance of the
data store, etc. The data store information and network information can
be used to determine an expected overall response time of a particular
client.

[0353] The access/priority field 220 can also include a priority level
ranking of the client 102 identified by the client ID. A higher priority
level ranking can indicate that it is less desirable to source data from
a particular client because of the relative importance of applications
executing thereon, the user of the client, or other reasons. The
information can also be used to generate the sourcing rank for each entry
214, as described in greater detail below with reference to FIG. 12. In
some cases, information other than the information in the access/priority
field 220 can be used in determining which instance of the data block to
source, such as the information in the instance ID field 216.

[0354] Each entry 214 can also include age information in an age field
222. The age field 222 can be used to determine how long a particular
instance of a data block has existed in the primary storage subsystem
117. For example, it may be generally preferable to use newer instances
instead of older entries, or vice versa. The age field 222 in one
embodiment includes an age ID which is an alphanumeric indication of when
the entry 214 was added or revised relative to other data blocks. For
instance, the age ID may be a unique identifier for the particular data
block or instance of the data block, or may be a unique identifier
associated with a particular storage operation, such as a backup, backup
catalog, or other storage operation associated with the entry.

[0355] In some instances, the client-side signature repository 121 can
determine that a particular entry 214 is a new entry if the age field 222
indicates that it was added to the client-side signature repository 121
after a previous backup operation. Further, if the particular entry 214
is the first entry for a signature block 206, the system 100, in certain
embodiments, can determine that the data block and corresponding
signature are new to the primary storage subsystem 117 and therefore do
not yet reside in the secondary storage subsystem 118. If the system
determines that the entry 214 resided in the client-side signature
repository 121 prior to a previous secondary copy operation that involved
the data block corresponding to the entry 214, the system, in some
embodiments, can determine that the instance of the data block
corresponding to the entry 214 has already been copied to the secondary
storage subsystem 118 (e.g., has already been involved in a back up).

[0356] Because the clients 102 are frequently generating and modifying
primary data stored in the primary storage devices 104, it can in some
cases be beneficial to track whether a signature block 206 has been
modified since a previous backup. This can be done using a copy operation
flag 212. The copy operation flag 212 can indicate the time and/or date
of a previous copy operation, whether the signature block 206 has been
modified since a previous copy operation, whether the data block
corresponding to the signature block has been part of a previous copy
data set and stored in the secondary storage subsystem 118 (e.g., the
signature block is not a new signature block), or any combination
thereof. For example, during a copy operation, the system 100 can
identify signature blocks that have been modified since a previous backup
by referring to the copy operation flag 212. By identifying signature
blocks that have been modified, the system 100 can identify data
corresponding to the modified signature blocks that has changed and/or
data that may be unique to the primary storage subsystem 117 (e.g., does
not reside or is unlikely to reside in the secondary storage subsystem
118). Thus, in some embodiments, rather than reading the data in a copy
data set to identify data that may be unique to the primary storage
subsystem 117 and/or has changed, the system 100 can refer to the
signature information in the client-side signature repository 121
corresponding to the data in the copy data set. In this manner, the
system 100 can reduce the amount of data being read and time spent to
identify modified data, and can more quickly identify which data might be
unique to primary storage, e.g., for performing a deduplicated secondary
copy.

[0357] Further, the copy operation flag 212 can indicate that the
signature block 206 has been modified since a previous copy operation if
the signature block 206 is either new or has been revised since the
previous copy operation. For example after a copy operation is completed,
the copy operation flag 212 can be reset. Thereafter, if the signature
block 206 is edited, the copy operation flag 212 can be set, indicating
that the signature block 206 may contain information that has not yet
been involved in a copy operation. Furthermore, each time a new signature
block is generated, the copy operation flag can 212 can be set indicating
that the signature block and corresponding data block have not been
involved in a copy operation.

[0358] The signature block 206 and/or corresponding entries 214 can
contain fewer or more pieces of information than what is illustrated in
the examples shown in FIGS. 2A and 2B. For example, the signature block
206 can include date data, such as the date when the signature block 206
was created or modified, etc. In some embodiments, the entries 214
include file identifiers that indicate to which file an entry 214
belongs. The file identifiers can be located in the location field 218,
in another field, or in a separate field. Furthermore, the entries 214
can include organizational data that indicates where the data block
corresponding to the entry 214 is located with respect to other data
blocks in a particular file, etc.

[0359]FIG. 3 is a flow diagram illustrative of one embodiment of a
routine implemented by a storage system 100 for performing a secondary
copy operation (e.g., a backup, archive, or snapshot operation) using a
client-side signature repository 121.

[0360] At block 302, a request is received to perform a secondary copy
operation for a data set associated with a first client computing device
102 of plurality of client computing devices 102. For instance, a storage
policy implemented on a storage manager 140 may trigger a secondary copy
operation on a scheduled basis, or a user can trigger a secondary copy
operation via interaction with a user interface. In one embodiment, the
storage manager 140 forwards an instruction to perform the secondary copy
to a data agent 142 executing on the first client computing device 102.
The copy data set can generally be any grouping of data associated with
the first client 102, and can include one or more files, directories, or
the like. In one embodiment, the client data set includes one or more
sub-clients, as described herein.

[0361] At block 304, the storage system 100 generates signatures for the
individual data blocks in the copy data set. Depending on the embodiment,
the signatures can be generated by different entities in the storage
system 100. For example, in one embodiment, a signature generator 123 on
the first client 102 generates the signatures locally. As another
example, signatures can be generated by the client-side signature
repository 121, which can be separate from and/or remote from the
client(s) 102.

[0362] At block 306, the agent 102 of the client-side signature repository
121 (or other appropriate component) consults the signature repository
204 to locate data blocks in the copy data set within the primary storage
subsystem 117. For instance, while the first client 102 may store actual
copies of all data blocks in the copy data set, it may be useful to
source the data blocks from data stores associated with other ones of the
clients 102 for the purposes of creating and transmitting the secondary
copy, as described previously.

[0363] At block 308, the storage system 100 determines which client(s) to
source the individual data blocks from to compile the copy data set. For
example, the agent 102 may access information in the client-side
signature repository 204 associated with copies of the individual data
blocks that reside in the primary storage subsystem 117. Such information
can include any type of information sufficient to select particular
copies of the data block to source, and in some embodiments includes
information organized along the lines of the signature blocks 206 of
FIGS. 2A and 2B, such as the access/priority information 220 and/or age
222 information. Where there are multiple copies of a data block within
the primary storage subsystem 117, the agent 202 may compare the accessed
information to a sourcing policy or other criteria to determine which
copy to source for inclusion in the copy data set. Additional techniques
for determining which copy of the data block to source for the purposes
of compiling a copy (or restore) data set are described herein, e.g.,
with respect to FIG. 12.

[0364] At block 310, the data blocks in the copy set are sourced from the
clients 102 as determined at block 308. Depending on the sourcing
determinations, a first subset of one or more data blocks may be sourced
from the first client 102 and the remainder of the data blocks may be
sourced from one or more second clients 102. Depending on the sourcing
determination for any particular copy operation, a variety of scenarios
are possible. For instance, in some cases, all data blocks may be sourced
from the first client 102. Conversely, all of the data blocks may in
other scenarios be sourced from one or more clients 102 other than the
first client 102. In order to access the data blocks within the primary
storage subsystem 117, the agent of 202 of the client-side signature
repository 121 may refer to other information in the signature repository
121 in addition to the signature 208, such as the location information
218 of the signature block 206 described with respect to FIGS. 2A and 2B.

[0365] At block 312, the accessed data blocks are forwarded from the
primary storage subsystem 117 to the secondary storage subsystem 118. For
example, all of the sourced data blocks in the data set may be forwarded
to the agent 102 of the client-side signature repository 121 or to some
other central or shared location within the primary storage subsystem 117
for forwarding to a media agent 144. In some cases, a data agent or other
entity receives the data blocks and compiles the data blocks into a
packaged (e.g., formatted) copy data set before sending to the media
agent 144. In other embodiments, each source client 102 forwards the
datablocks it is responsible for directly to the secondary storage
subsystem 118.

[0366] At block 314, the media agent 144 or other appropriate component
within the secondary storage subsystem 118 creates the secondary copy by
conveying the data to one or more secondary storage devices 108 for
storage.

[0367]FIG. 4 is a state diagram illustrative of the interaction between
the various components of the storage system 100 with respect to an
exemplary collaborative copy operation where a copy data set associated
with a target client 102B is sourced from multiple clients 102, including
one or more clients 102A, 102C other than the target client 102B. For
purposes of the example, the illustrated embodiment has been simplified
to include interaction between the clients 102, one media agent 144, and
one storage device 108. In other embodiments, any of the media agents 144
and any of the storage devices 108, alone or in combination, can be used
for performing a collaborative copy operation from any combination of the
clients 102.

[0368] A collaborative copy operation (or other storage operation) can be
initiated in many different ways, such as at predetermined time
intervals, upon client request, upon storage manager 140 request, etc.
For example, a storage policy associated with the client 102B may dictate
that a copy operation occur daily, weekly, monthly or at some other
predetermined time interval. Alternatively, the copy operation can occur
based on manual selection by a system administrator via user interface.

[0369] In the illustrated example, signatures are generally generated
locally by the individual clients 102. Thus, as part of the current copy
operation, the signature generator 123 of the subject client 102B
generates signatures for data blocks in the copy data set (1A). The
client forwards (1B) the generated signatures to the client-side
signature repository 121. The agent (not shown) of the client-side
signature repository 121 in some cases may update the information in the
signature repository 204 as appropriate, e.g., to add entries 214
corresponding to the data blocks in the copy data set. In other cases,
the entries 214 were added previously, such as at the time the data was
originally written to the primary storage device 104 of the target client
102B.

[0370] Before the current copy operation, the client-side signature
repository 121 already included entries corresponding to some or all of
the data blocks previously stored in the primary storage devices 104
associated with the set of clients 102. Although in the illustrated
embodiment the client-side signature repository 121 is shared by multiple
clients, in some embodiments, each of the clients 102 is associated with
its own client-side signature repository 121. Furthermore, in certain
other embodiments, the client-side signature repository 121 generates the
data block signatures instead of the client signature generators 123.

[0371] The client-side repository 121 processes (2) the received
signatures in the copy data set to determine where to source the data
blocks from in the primary storage subsystem 117 for the purposes of
sending to the secondary storage subsystem 118, i.e., to carry out the
copy operation. In some cases, such as where the copy operation is a
deduplicated copy operation, the client-side signature repository 121 (2)
processes the signatures information related to the data blocks in the
copy data set to identify for transmission to the secondary storage
subsystem 118 only those the data blocks that are unique to the primary
storage (that don't exist in the secondary subsystem).

[0372] The client-side repository 121 (or other appropriate entity such as
a data agent 142 of the client 102B) in some embodiments transmits (3) a
copy data set index (FIGS. 13-14) to the media agent 144. As will be
described in greater detail herein, the copy data set index may be a data
structure including metadata forming a map of the secondary copy,
specifying the data blocks in the copy as well as their relative
organization. In the illustrated example, one or more of the clients 102
forward copies of the data blocks that form the copy data set to the
secondary storage subsystem 118. For instance, once the client-side
repository 121 determines which clients 102 the individual copies of the
data blocks in the copy data set are going to be sourced from, the
client-side repository 121 (or other appropriate component such as the
storage manager 140) instructs those source clients 102 to forward copies
of those data blocks to the media agent 144. In other embodiments, the
data blocks that form the copy data set are accumulated at a central
location (e.g., at the client-side repository 121), and the entire copy
data set is sent as a group to the media agent 144.

[0373] As shown, the target client 102B as well as one or more non-target
clients 102A, 102C may be selected as sources for at least some of the
data blocks. The client-side signature repository 121 may instruct the
respective clients (4A, 4B, 4C) to forward copies of the data blocks that
are going to be sourced from each respective client 102 to the secondary
storage subsystem 118. In turn, the target client 102B forwards (5A) the
requested data blocks to the media agent 144 or other appropriate
component in the secondary storage subsystem 118. Where at least some of
the data blocks are to be sourced from clients 102A, 102C other than the
target client 102B, e.g., based on a data sourcing policy, those data
blocks are forwarded (5B), (5C) by the non-target clients 102A, 102C to
the media agent 144. Example data sourcing policies will be described in
greater detail below with reference to FIG. 12. In this manner, resource
utilization in the primary storage subsystem 117 can be allocated as
desired. For instance, the amount of processing performed by the target
client 102B and/or the amount of downtime of the target client 102B to
perform the copy operation can be reduced.

[0374] The media agent 144 (6) processes the data received from the
primary storage subsystem 117. To process the data, the media agent 144
can store the copy data set index or other map of the files and data
within the secondary copy. Once the media agent 144 has processed the
received data, the media agent creates (7) the secondary copy by writing
the copy data set to the storage device(s) 108.

[0375] One skilled in the art will appreciate that all of the components
of storage system 100 are not necessary to perform the copy operation,
and that the processes described herein can be implemented in any number
of ways without departing from the spirit and scope of the description.
For example, one or more of the clients 102, the storage manager 140, or
another appropriate component may perform the functions described in
association with the client-side signature repository.

[0376]FIG. 5 is a flow diagram illustrative of an embodiment of a routine
500 implemented by a storage system 100 for updating a client-side
signature repository 121. For example, routine 500 can apply to
embodiments described with reference to FIGS. 1A-1J, 2A, and 2B. While
specific steps of the example routine 500 provided below are described as
being performed by a particular component of the storage system 100, the
steps of the routine 500 can generally be implemented by other components
in other embodiments, such as any one, or a combination, of the storage
manager 140, one or more of clients 102, the agent 202 of the client-side
signature repository 121, one or more media agents 144, and/or one or
more of the secondary storage devices 108.5

[0377] At block 502, the storage system 100 tracks storage operations
associated with one or more of the clients 102. The storage operations
may include, but are not limited to the generation of a new file, the
modification of an existing file, the deletion of an existing file, the
saving of a file, etc. For instance, the clients 102 may track their own
storage operations, or central, shared component, such as the agent 202
of the client-side signature repository 121 may track the storage
operations for multiple ones of the clients 102.

[0378] At block 504 the storage system 100 identifies data that has been
modified within a primary storage device 104 as a result of tracked
primary storage operation (e.g., a newly written or modified file). For
instance, to identify the data that has been modified, the storage system
100 can detect or otherwise track or identify each write to the data
store. In some instances, each time data is written to or deleted from
the primary storage device 104, the storage system 100 records the
location of the data that has been modified within the primary storage
device 104, as well as additional information. Furthermore, the system
100 can identify the data blocks corresponding to modified data. For
example, a file may be formed from six data blocks. A user may edit and
save the file. Upon saving the file, the first five data blocks remain
the same, but the sixth data block changes and an additional four data
blocks can be added (for a total of ten data blocks). The storage system
100 can identify the file and/or the data blocks that have changed
together as a group, or can identify the data blocks separately on an
individual basis. Furthermore, the system 100 can track the storage
location of the data blocks that make up the file.

[0379] At block 506, the storage system 100 generates signatures for the
data blocks that make up the identified data. As discussed in greater
detail above with reference to FIG. 2A, the signature can be generated
using a hash function, or some other function capable of uniquely
identifying the data blocks or substantially uniquely identifying the
data blocks. In some embodiments the storage system 100 can generate the
signature for the data blocks during or otherwise in association with the
storage operation. In certain embodiments the storage system 100
generates the signature for the data blocks after the storage operation
has been completed. In other embodiments, signatures for newly added or
modified data can be generated at some other time, e.g., based on a
preference included in a storage policy. For example, a storage policy
can specify a frequency with which signatures should be generated for
data blocks corresponding to modified data. Or a storage policy can
specify that signatures are generated once a particular application has
been closed, once a client computer is to be shut down, once a day, or
some other interval, as desired. In one embodiment, signatures are
generated local to each client 102 by the signature generator 123
residing on the client 102. In other cases, signatures 123 are generated
by a shared component, such as the agent of the client-side signature
repository 121.

[0380] At block 508 the storage system 100 updates the client-side
signature repository 121. For instance, the agent 202 of the client-side
signature repository 121 (or other appropriate component) can determine
if (1) a generated signature is new to the client-side signature
repository 121, or if instead (2) the client-side signature repository
121 already includes the signature. For instance, where the client-side
signature repository 121 is organized using signature blocks 206, if the
client-side signature repository 121 includes the generated signature, it
will already include a signature block 206 for that signature, and the
agent 202 can revise the existing signature block 206 to add an entry 214
corresponding to the newly added data block instance.

[0381] In some instances, such as when a data block has been overwritten
or deleted, the agent 202 can remove an entry from a signature block 206.
Also, if a generated signature is not already included in the client-side
signature repository 121, the client-side signature repository 121 can
generate a new signature block 206 containing the new signature as well
as an entry with additional information regarding the data block used to
generate the signature as discussed in greater detail above with
reference to FIGS. 2A and 2B. As mentioned previously, the client-side
signature repository 121 can include signatures corresponding to data
blocks found in one client or multiple clients.

[0382] Furthermore, if the storage system 100 determines that a data block
has been removed and the entry being deleted is the last entry of a
signature block 206, in certain embodiments, the storage system 100 can
remove the signature block from the client-side signature repository 121.
In this way, the client-side signature repository 121 accurately
represents the data currently residing in the primary storage subsystem
117.

[0383] One skilled in the art will appreciate that routine 500 can include
fewer, more, or different blocks than those illustrated in FIG. 5. For
example, the storage system 100 can update the client-side signature
repository 121 based on a storage policy, a user request, identified
storage operations, etc. The storage policy can indicate a predefined
schedule when the client-side signature repository 121 should be updated.
For example, the client-side signature repository 121 can be updated
every five minutes, every hour, at the end of each day or business day,
at the end of each week, etc. In some embodiments the client-side
signature repository 121 is updated each time the client computer is to
be shut down. Moreover, the described steps may be performed differently
in some embodiments. For instance, the agent 202 of the client-side
signature repository 121 may decide to retain a signature block 206 in
some cases even where the only copy of the corresponding data block in
the primary storage subsystem 117 is deleted. In this way, the
client-side signature repository 121 can additionally track data blocks
that have previously resided in primary storage. In such embodiments, the
signature block 206 can include a flag indicating that no copies of the
corresponding data block currently reside in the primary storage
subsystem 117. For example, the indicator can simply be that the
instances field 210 indicates zero entries. In certain embodiments, the
agent 202 of the client-side signature repository 121 determines whether
or not a signature block with zero entries should be deleted based on
whether or not an instance of the corresponding data block was previously
copied to the secondary storage subsystem 118 (e.g., as part of a backup
operation). If the data block has been previously copied to the secondary
storage subsystem 118, the client-side signature repository 121 may
decide not to delete the signature block 206, whereas, if the client-side
signature repository 121 determines that the data block was not
previously copied to the secondary storage subsystem 118, the client-side
signature repository 121 may decide to delete the signature block 206, or
vice versa, as desired.

[0384]FIG. 6 is a state diagram illustrative of the interaction between
the various components of an example of the storage system 100 with
respect to a secondary copy operation (e.g. a backup operation, snapshot
operation, auxiliary copy operation, archive operation, etc.) where data
blocks are sourced only from the target client 102B. The copy operation
may be a deduplicated operation, as will be described. For purposes of
the example, the illustrated embodiment has been simplified to include
interaction between one client 102B, 102A, one media agent 144, and one
storage device 108. In other embodiments, any of the media agents 144 and
storage devices 108, alone or in combination, can be used for performing
a copy operation from any combination of the clients 102.

[0385] The client 102B (1A) generates signatures of data blocks
corresponding to data that has been modified within the primary storage
device 104, and (1B) updates the client side repository 121 with the
generated signatures. Although in the illustrated embodiment there is one
client-side signature repository 121 for three clients 102, in some
embodiments, each of the clients 102 is associated with its own
client-side signature repository 121. Furthermore, in certain
embodiments, the client-side signature repository 121 generates the
signatures for the one or more clients with which it is associated, and
those clients 102 do not generate the signatures locally.

[0386] In an embodiment, the system 100 initiates a copy operation for a
copy data set (e.g., of one or more files, file system volumes, etc.)
stored within a primary storage device 104 of a target client 102B. Upon
initiating the copy operation, the client-side signature repository 121
(2) processes the copy operation request and identifies data blocks to
send to the secondary storage subsystem 118 as part of the copy
operation.

[0387] For instance, the client-side signature repository 121 can be used
to carry out a deduplicated copy operation, where only those data blocks
unique to the primary storage subsystem 117 (i.e., do not already reside
in the secondary storage subsystem 118) that are part of the copy data
set are sent to the secondary storage subsystem 118.

[0388] The copy data set for any of the embodiments described herein can
vary depending on the type and scope of the copy operation being
performed. For example, the copy operation can be a full backup or
incremental backup of either the entire data store or only portions
thereof (e.g., one or more files, folders, etc.). In a full backup of the
entire primary storage device 104, the copy data set can include the
entire data set found in the primary storage device 104 associated with
the client 102B. In an incremental backup of the primary storage device
104, the copy data set can include all of the data in the primary storage
device 104 that has changed since a previous backup. Similarly, for a
full or incremental backup of one or more files, the copy data set can
include all the data in the one or more files or the data in the one or
more files that has changed since a previous backup, respectively.

[0389] As mentioned, the client-side signature repository 121 can identify
the data blocks unique to primary storage that correspond to the copy
data set. In this example, the data blocks unique to primary storage
refer to the data blocks stored in the storage device 104 associated with
the client 1026 but not found in the secondary storage subsystem 118.
However, in some embodiments, the data blocks unique to the primary
storage refers to data blocks that are in any of the clients 102 but that
do not already reside in the secondary storage subsystem 118. For
example, if the copy operation request is for full or incremental backup
of a single file of the client 102B, the client-side signature repository
121 identifies the data blocks unique to primary storage that form at
least a portion of the single file.

[0390] In some embodiments, to identify the data blocks that are unique to
primary storage, the client-side signature repository 121 identifies
signature blocks that have been modified since a previous copy operation.
For example, the client-side signature repository 121 identifies
signature blocks with a copy operation flag 212 set to indicate that the
signature block has been modified since a previous copy operation.

[0391] In certain embodiments, the client 102B or the media agent 144
identify the data blocks that are unique to primary storage by reviewing
signature block information. For example, in a full backup of the entire
data store associated with the client 102B, the client 102B or the media
agent 144 can identify the data blocks that are unique to primary storage
using the copy operation flag 212, or by comparing a creation date of a
signature block with the date of the last copy operation.

[0392] Once the data blocks that are unique to primary storage have been
identified, the client-side signature repository can 121 can in some
embodiments (3) provide a copy data set index to the secondary storage
subsystem 118 (e.g., to the media agent 144). The copy data set index can
provide information regarding the data blocks corresponding to the data
associated with the copy operation, as well as a map indicating the
relationship between the different data blocks. One embodiment of a copy
data set index is described in greater detail below with reference to
FIG. 13. In some embodiments, the copy data set index is generated and
communicated to the secondary storage subsystem 118 (e.g., to the media
agent 144) by the client 102 whose data set is being copied rather than
the client-side signature repository 121. In other embodiments, the media
agent 144 may generate the copy data set index.

[0393] The client 102B (4) provides the identified data blocks (e.g.,
those that are unique to primary storage subsystem 117) to the secondary
storage subsystem 118. In some embodiments, the client 1028 provides the
data blocks to the client-side signature repository 121, which in turn
provides the data blocks to secondary storage. In certain embodiments,
the client-side signature repository 121 requests the client(s) 102 to
provide the identified data blocks to the media agent 144. In some cases,
the media agent 144 requests the identified data blocks from the client
102B.

[0394] Upon receiving the data blocks from the primary storage subsystem
117, the media agent 144 (5) processes the data blocks as part of the
copy operation. For instance, the media agent 144 may update its index in
view of the copy operation as described herein. In some cases, the media
agent 144 stores the copy data set index for future use. The media agent
144 then conveys the copy data set to the storage device 108 for storage
thereon.

[0395] One skilled in the art will appreciate that all of the components
of storage system 100 are not necessary to perform the copy operation,
and that the processes described herein can be implemented in any number
of ways without departing from the spirit and scope of the description.
In one embodiment, the client-side signature repository 121, client 102b,
or media agent 144 can identify some or all of the unique data blocks in
the primary storage subsystem 117 (that aren't already in the secondary
storage subsystem 118) regardless of whether the unique data blocks form
part of a copy data set. The unique data blocks can then be sent to the
media agent 144 (e.g., on a scheduled basis, or as part of a copy
operation along with data blocks that are associated with the copy
operation) for storage in the secondary storage subsystem 118. In this
way, the secondary storage subsystem 118 can accumulate copies of data
blocks that exist in the primary storage subsystem 117, e.g., before
certain data blocks form part of a copy data set. This technique can take
advantage of available bandwidth to simplify future deduplicated copy
operations, for example.

[0396] FIG. 7 is a flow diagram illustrative of one embodiment of a
routine 700 implemented by a storage system 100 for executing a
collaborative copy operation of data using a client-side repository 121,
where the copy operation is a deduplicated copy operation. One skilled in
the relevant art will appreciate that the elements outlined for routine
700 may be implemented by one or many computing devices/components that
are associated with the storage system 100. For example, routine 700 can
be implemented by any one of, or a combination of, the storage manager
140, one or more clients 102, the client-side signature repository 121,
one or more media agents 144, and/or one or more of the storage devices
108.

[0397] At block 701, the storage system 100 receives a secondary copy
operation request associated with a copy data set (e.g., a subclient) of
a target client 102B, such as a request to perform a copy operation.
Because the copy operation is deduplicated, at block 702, the storage
system 100 identifies data blocks involved with the copy operation that
are unique to primary storage subsystem 117 and don't already exist in
the secondary storage subsystem 118.

[0398] For the identified data blocks that are unique to primary storage,
the storage system 100 determines at block 706 consults the
client-signature repository 121 to determine whether copies of the data
block the data block exist in the data stores of any non-target clients
102 and, if so, determines whether the data block will be sourced from
another client 102, or will instead be sourced from the target client
102B. To identify whether the data block is located in another client
102, the storage system 100 can analyze the signature information (e.g.,
signature blocks 206) corresponding to the data blocks in the copy data
set. For example, if a signature block 206 indicates that there are
multiple instances of a data block corresponding to a particular
signature in field 210, includes multiple entries 214, and/or includes
multiple Client IDs in the location field 218, the storage system 100 can
determine that multiple copies of the data blocks exist in primary
storage. Or, where a shared client-side signature repository 121 is not
used and each client 1-2 instead maintains its own separate client-side
signature repository 121, the storage system 100 can access the
client-side signature repositories 121 of the individual clients 102 to
identify whether any non-target clients 102 have a copy of the data
block.

[0399] Upon determining that a data block is to be sourced from a
non-target client at block 704, the storage system 100 at block 706
identifies the location of the data block in the primary storage
device(s) 104 associated with that client 102. To identify the location
of the data block in the other, non-target client 102, the storage system
100 can review the signature blocks 206 corresponding to the data blocks
in the copy data set. For example, the storage system 100 can review the
entry 214 corresponding to the data block located in the other client
102. The entry 214 can include the location information of the data block
within the other client 102.

[0400] On the other hand, if the storage system 100 determines that the
data block will be sourced from the target client 102 (e.g., because that
is the only copy of the data block), the storage system 100 identifies
the location of the data block in the primary storage device 104
associated with the target client 102 at block 708. Sourcing policies for
determining which clients 102 to source data blocks from are described in
greater detail herein, e.g., below with reference to FIG. 12.

[0401] Once the location of the identified data block that is unique to
primary storage has been identified, the storage system 100 performs the
copy operation at block 710. The data block is retrieved from the
identified location in the primary storage device 104 associated with the
determined source client 102. In addition, the signature information,
such as the corresponding signature block 206 or portion thereof can be
retrieved from the client-side signature repository 121 and sent to the
secondary storage subsystem 118.

[0402] While described with respect to a single data block for the
purposes of clarity, the retrieved data (data blocks and/or signature
information) can be sent from their respective locations either
individually or bundled together. Moreover, signatures corresponding to
the data blocks that are not unique to the primary storage subsystem 117
(already exist in the secondary storage subsystem 118) are generally sent
to the secondary storage subsystem 118 instead of copies of the data
blocks themselves. The secondary storage subsystem 118 utilizes the
signature to identify the pre-existing copy of the data block in the
secondary storage device(s) 108 for use in creating the secondary copy.

[0403] One skilled in the art will appreciate that routine 700 can include
fewer, more, or different blocks than those illustrated in FIG. 7.
Moreover, a number of alternative embodiments are possible. For instance,
in some cases the secondary copy operation is not a deduplicated copy
operation, and copies of all of the data blocks in the copy data set are
forwarded to the secondary storage subsystem 118 instead of just copies
of those data blocks that are unique to the primary storage subsystem
117.

[0404]FIG. 8 is a flow diagram illustrative of an embodiment of a routine
800 implemented by a storage system 100 for using a client-side
repository 121 to perform a restore operation. One skilled in the
relevant art will appreciate that the elements outlined for routine 800
may be implemented by one or many computing devices/components that are
associated with the storage system 800. For example, routine 800 can be
implemented by any one, or a combination of, the storage manager 140, one
or more clients 102, the client-side signature repository 121, one or
more media agents 144, and/or one or more storage devices 108.

[0405] At block 801, the storage system 100 receives a request to restore
a restore data set to a target client 102B. At block 802, the storage
system 100 receives signatures of data blocks in the restore data set.
The storage system 100 can receive the signatures of the data blocks to
be restored from the media agent 144, for example. In other cases, the
signatures can be obtained from the target client 102B, the component
requesting the restore, the storage manager 140, and/or the client-side
signature repository 121.

[0406] For each data block to be restored, the storage system 100
determines whether the data block is located in the primary storage
subsystem 117 at block 804. For instance, as described in greater detail
above, with reference to FIG. 8, the storage system 100 can determine
whether the data block is located in the primary storage subsystem 117 by
reviewing the signature blocks 206 stored in the client-side signature
repository 121.

[0407] In some embodiments, if a signature corresponding to a data block
to be restored is located in the client-side signature repository 121 or
if an existing signature block 206 has at least one entry 214, the
storage system 100 determines that the data block is located in the
primary storage subsystem 117.

[0408] Upon determining that the data block is located in the primary
storage subsystem 117, the storage system 100 identifies the location of
the data block, as illustrated at block 806. For instance, copies of the
data block may reside in the target client 102B and/or any of the other
non-target clients 102. FIGS. 9 and 10, described below, illustrate
examples of restore operations where data is sourced from only the target
client 102B (FIG. 9) and where data is collaboratively sourced from
multiple ones of the clients 102 (FIG. 10).

[0409] On the other hand, if the information in the signature repository
116 indicates that the data block is not located in the primary storage
subsystem 117, the storage system 100 can request and receive the data
block from the secondary storage subsystem 118 at blocks 808 and 810,
respectively.

[0410] Once the data blocks located in the primary storage subsystem 117
have been identified and the data blocks not located in the primary
storage subsystem 117 have been received at the primary storage subsystem
117 from the secondary storage subsystem 118, the storage system 100 can
restore the data, as illustrated in block 812. One skilled in the art
will appreciate that routine 800 can include fewer, more, or different
blocks than those illustrated in FIG. 8.

[0411]FIG. 9 is a state diagram illustrative of the interaction between
the various components of the storage system 100 with respect to an
example of an implementation of a restore operation. For purposes of the
example, the illustrated embodiment has been simplified to include
interaction between one client 102B, one media agent 144, and one storage
device 108. In other embodiments, any of the media agents 144 and any of
the storage devices 108, alone or in combination, can be used for
performing a restore operation of any combination of the clients 102. For
instance, an example of a collaborative restore operation is described
with respect to FIG. 10, where data is sourced from other ones of the
clients 102 in performing the restore operation. Although in the
illustrated embodiment the client-side signature repository 121 is
generally central to and associated with multiple clients 102, in some
embodiments, each of the clients 102 is associated with a dedicated
client-side signature repository 121.

[0412] In an embodiment, the storage manager 140 or other appropriate
component initiates a restore by instructing the media agent 144 a
restore data set be restored to a target client 102B. The restore request
can be initiated by one or more of the components of the storage system
100. Such a restore may initiate upon the occurrence of some
predetermined criteria, such as a re-boot after a power outage,
information store error, or some other condition that causes a client
system to go off-line, addition of a new client, or the like. In one
embodiment, the data from one client system 102B can be restored to
another client 102A, 102C.

[0413] In response to the restore request, the client-side signature
repository 121 (1) receives the signatures of the data blocks in the
restore data set. The data blocks involved in the restore operation can
include the data blocks that are to be restored to a target client 102B.
Although the illustrated embodiment shows the client-side signature
repository 121 receiving the signatures from the media agent 144, the
client-side signature repository 121 can receive the signatures from
various components of the storage system 100. For example, the
client-side signature repository 121 can receive the signatures from the
component initiating the restore request, from the client 102B, or can
generate the signatures itself.

[0414] In some embodiments, a component of the storage system 100 includes
an index of the restore data set, which can include the signatures
corresponding to the data blocks in the restore data set as well as a
mapping of the organization of the restore data set. The index can be a
copy data set index that is generated during the secondary copy
operation, for example, or can be derived therefrom. In certain other
embodiments, the client-side signature repository 121 already has a copy
of the index and the index is therefore not sent from the secondary
storage subsystem 118 to the primary storage subsystem 117. For instance,
the client-side repository 121 in some cases retains copies of indexes
associated with secondary copy operations for later use in the restore
operation.

[0415] Once the client-side signature repository 121 receives the
signatures of the data blocks in the restore data set, the client-side
signature repository 121 (2) identifies data blocks in the restore data
set that are already located in the primary storage subsystem 117. In the
illustrated embodiment, the client-side signature repository 121
identifies copies of the data blocks in the restore data set that already
reside in the target client 102B. However, in other embodiments, the
system can implement a collaborative restore operation (FIG. 10) in which
data blocks are sourced from non-target clients 102 instead of or in
addition to the target client 102.

[0416] For data blocks for which copies do not reside in the primary
storage subsystem 117 (e.g., where no corresponding signature was found
in the client-side signature repository 121, or where the information in
the client-side repository 121 otherwise indicates the data block is not
in primary storage), the client-side signature repository 121 (or other
appropriate component) (3) requests copies of the data blocks from the
media agent 144. For instance, the client-side signature repository 121
can request the data blocks individually from the media agent 144 and/or
can bundle multiple data block requests together. In turn, the media
agent 144 can (4) request and receive the data blocks from the storage
device 108 and the client-side signature repository 121 can (5) receive
the data blocks from the media agent 144. Similar to the client-side
signature repository 121, the media agent 144 can send the data blocks
individually or bundle multiple data blocks together.

[0417] Once the client-side signature repository 121 has identified the
location of the data blocks within primary storage and received the data
blocks not in primary storage from secondary storage, the client-side
signature repository 121 can (6) forward information to the client 102
that is sufficient to perform the restore operation. For instance,
references (e.g., location information) to the data blocks in the restore
set that already reside in the target client 102B are forwarded to the
target client 102B along with copies of the data blocks received from the
secondary storage subsystem 118. In addition to the location information
of the data blocks stored in the primary storage device 104 and the data
blocks received from secondary storage subsystem 118, the client-side
signature repository 121 can transmit a restore data set index that
provides information regarding how the data blocks in the restore data
set are organized. The target client 102B can use the received location
information, received data block copies, and/or received restore data set
index to create the restored data set.

[0418] One skilled in the art will appreciate that all of the components
of storage system 100 are not necessary to store and restore data blocks,
and that the processes described herein can be implemented in any number
of ways without departing from the spirit and scope of the description.
For example, in an embodiment, the client-side signature repository 121
does not perform any of the processing steps. In such an embodiment, the
client 102B or media agent 144 can query the client-side signature
repository 121 for the signatures corresponding to the data blocks
involved in the restore operation. The client 102B or media agent 144 can
then identify the data blocks stored in primary storage as described
previously. In some embodiments, the client-side signature repository 121
can simply transmit the signatures of the data blocks not located in
primary storage to the media agent 144 without requesting the data blocks
in return. In response, the media agent 144 can transmit the data blocks
not found in primary storage directly to the client 102B for restore via
a network, bypassing the client-side signature repository 121.

[0419]FIG. 10 is a state diagram illustrative of the interaction between
the various components of a storage system 100 with respect to an
exemplary collaborative restore operation. For purposes of the example,
the illustrated embodiment has been simplified to include interaction
between the clients 102, one media agent 144, and one storage device 108.
In other embodiments, any of the media agents 144 and any of the storage
devices 108, alone or in combination, can be used for performing a
collaborative restore operation on any combination of the clients 102.
Although in the illustrated embodiment the client-side signature
repository 121 is associated with multiple clients, in some embodiments,
each of the clients 102 is associated with its own client-side signature
repository 121.

[0420] As described in greater detail above, with reference to FIGS. 8 and
9, the storage system 100 initiates a restore request and the CSR 121 (1)
receives signatures of data blocks in a restore data set that are to be
restored to a target client and (2) identifies data blocks in the restore
data set that are located in primary storage. In this embodiment, the
data blocks located in primary storage refers to all of the data blocks
located in any of the clients 102A, 102B, 102C, or other clients for
which the client-side signature repository 121 stores signature blocks.
However, as mentioned previously, in some embodiments, the data blocks
located in primary storage can refer to only the data blocks located in a
single client.

[0421] As discussed in greater detail above, with reference to FIGS. 8 and
9, the data blocks located in the primary storage subsystem 117 can be
identified using the signature blocks stored in the client-side signature
repository 121. Once identified, the location information of the data
blocks located in the primary storage subsystem 117 can also be
retrieved, as described previously. For example, the client-side
signature repository 121 can review the location information 218 of the
entries 214 of the signature block 206 corresponding to the data blocks
in the restore data set to identify one or more locations within the
primary storage subsystem 117 where the data block is located.

[0422] In this example, some of the data blocks to be restored to a first
location in the client 102B can be located in a second location in the
client 102B and/or in one or more of the other clients 102A, 102C.
Accordingly, the client-side signature repository 121 can identify which
of the different locations will be used as within the primary storage
subsystem 117 to source to each data block based on a data sourcing
policy, which will be described in greater detail below with reference to
FIG. 12.

[0423] Once the sources of the respective data blocks in the restore data
set have been identified, the client-side signature repository 121 (3A),
(3B) requests and receives the data blocks to be used in the restore from
the source client(s) 10 based on the data sourcing policy. In other
cases, the data blocks are forwarded directly to the target client 102B
without first being transmitted to the client-side repository 121. In
addition, the client-side signature repository 121 (3C) requests the data
blocks not already residing in the primary storage subsystem 117 from the
media agent 144, and the media agent 144 in turn requests and receives
(4) the data blocks from the storage device 108. The client-side
signature repository 121 then receives (5) the data blocks from the media
agent 144. In some cases, even if a copy of one or more of the data
blocks in the restore data set resides in the primary storage subsystem
117 (e.g., in one of the non-target clients 102A, 102C), the data block
may nonetheless be sourced from the secondary storage subsystem 118. For
instance, the sourcing policy may dictate that the client(s) 102 that
stores the copy of the data block should not be interrupted for the
purposes of accessing the data block, such as where that client 102 is
performing critical tasks or the like.

[0424] In the illustrated embodiment, once the data blocks have been
received from the clients 102A, 102C and secondary storage, the
client-side signature repository 121 can (6) transmit the data to the
client 102B. The target client 102B may compile the restore data set by
combining the received data with any data blocks that are sourced from
the target client 102B, and restore the data set to the primary storage
device 104, completing the restore operation. In other configurations,
the entire restore data set is compiled at the client-side repository 121
and then communicated to the target client 102B.

[0425] In some embodiments, the client-side signature repository 121 is
also updated in view of the data that is copied to the primary storage
subsystem 117 during the restore operation. For instance, the client-side
signature repository 121 can be updated to reflect data blocks that were
received from the secondary storage subsystem 118 during the restore and
written to the primary storage device 104 associated with the target
client 102B. Moreover, the client-side signature repository 121 can be
updated to reflect copies of data blocks that were communicated from any
non-target clients and written to the primary storage device 104
associated with the target client 102B.

[0426] One skilled in the art will appreciate that all of the components
of storage system 100 are not necessary to store and restore data blocks,
and that the processes described herein can be implemented in any number
of ways without departing from the spirit and scope of the description.
For example, in an embodiment, the client-side signature repository 121
does not perform any of the processing steps. In such an embodiment, the
client 102B or media agent 144 can query the client-side signature
repository 121 for the signatures corresponding to the data blocks
involved in the restore operation. The client 102B or media agent 144 can
then identify the data blocks stored in primary storage as described
previously. In some embodiments, the client-side signature repository 121
can simply transmit the signatures of the data blocks not located in
primary storage to the media agent 144 without requesting the data blocks
in return. In reply, the media agent 144 can bypass the client-side
signature repository 121 and transmit the data blocks not found in
primary storage directly to the client 102B for restore via a network.
Similarly, the clients 102A, 102C can bypass the client-side signature
repository 121 and transmit the data blocks to be restored from the
clients 102A, 102C directly to the client 102B via a network.
Furthermore, in some embodiments, multiple client-side signature
repositories 121 can be used. For example, each client 102 can be
associated with its own client-side signature repository 121. The
client-side signature repositories 121 can communicate with each other
during the restore to effectuate the various processes described above.

[0427]FIG. 11 is a flow diagram illustrative of an embodiment of a
routine 1100 implemented by a storage system 100 for performing a
collaborative restore operation. One skilled in the relevant art will
appreciate that the elements outlined for routine 1100 may be implemented
by one or more computing devices/components that are associated with the
storage system 1100. For example, routine 1100 can be implemented by any
one, or a combination of, the storage manager 140, one or more clients
102, the client-side signature repository 121, one or more media agents
144, and/or one or more storage devices 108.

[0428] At block 1101, the storage system 100 receives a request to restore
a restore data set to a target client 102B.

[0429] At block 1102, the client-side signature repository 121 receives
signatures of data blocks in the restore data set. The client-side
signature repository 121 may be shared by the clients, or separate
dedicated client-side signature repositories may be associated with some
or all of the clients 102. At block 1104, the agent of the client-side
signature repository 121 reviews the information in the client-side
signature repository 121 to identify data blocks in the restore data set
that are located in the primary storage subsystem 117 in any of the
manners described herein.

[0430] For each data block in the restore data set that is located in the
primary storage, the agent 202 of the client-side signature repository
121 determines whether the data block already resides in the primary
storage device(s) 104 associated with the target client 102B, at block
1106. For instance, where signature information is organized in signature
blocks 206, the agent 202 of the client-side signature repository 121 can
review the entries 214 of the signature blocks 206 corresponding to the
data blocks located in the primary storage subsystem 117 to determine
whether the data block is located in the primary storage device(s) 104
associated with the target client 102B. For example, the location
information 218 in each entry 214 can include a client ID indicating
which client 102 includes a copy of the data block and/or indicating the
physical location of the data block within the storage device 104
associated with the client 102.

[0431] If it is determined that the data block is located in the storage
device 104 associated with the target client 102B, the agent 202 of the
client-side repository 121 can identify the location of the data block at
block 1108, e.g., by referring to information provided in the location
field 218 in the entry 214 of the corresponding data block. On the other
hand, if the storage system 100 determines that the data block is not
located in the target client 102B, the storage system 100 can request and
receive the data block from another client 102, at block 1110. The source
client 102 can be determined based on a data sourcing policy, which will
be described in greater detail below with reference to FIG. 12.

[0432] The agent of the client-side repository 121 also identifies data
blocks not located in the primary storage subsystem 117, and those data
blocks are requested and received from the secondary storage subsystem
118. In some cases where a data block does not exist in the storage
device 104 associated with the target client 102B, even if a copy of the
data block does reside in one of the other clients 102, it is nonetheless
sourced from the secondary storage subsystem 118 based on the sourcing
policy. In some other embodiments, the sourcing policy specifies that,
even if a copy of the data block is found in the storage device 104
associated with the target client 1026, the data block is still sourced
from one of the non-target clients 102 or from the secondary storage
subsystem 118.

[0433] At block 1112 the data set is restored to the primary storage
device 104 of the target client 1026.

[0434] One skilled in the art will appreciate that routine 1100 can
include fewer, more, or different blocks than those illustrated in FIG.
11.

[0435]FIG. 12 is a flow diagram illustrative of an embodiment of a
routine implemented by a storage system 100 for determining a location
from which to source data blocks for a storage operation. One skilled in
the relevant art will appreciate that the elements outlined for routine
1210 may be implemented by one or many computing devices/components that
are associated with the storage system 1210. For example, routine 1210
can be implemented by any one, or a combination of, the storage manager
140, one or more clients 102, the client-side signature repository 121,
one or more media agents 144, and/or one or more storage devices 108.

[0436] At block 1212, the storage system 100 identifies a data block
involved in a storage operation that is associated with a target client
102. The storage operation can include, but is not limited to, a copy
operation, restore operation, other storage operation, etc. The
identified data block can include a data block to be restored, that is
involved in the copy operation, and/or involved in another storage
operation.

[0437] At block 1214, the storage system 100 identifies the signature of
the current data block. In some embodiments, the storage system 100
identifies the signature by generating the signature of the data block.
In certain embodiments the storage system 100 identifies the signature of
the data block by retrieving the signature information from the
client-side signature repository 121, or other location.

[0438] At block 1216, the storage system 100 identifies the instances of
the data block that reside within the primary storage subsystem 117. In
some embodiments, where the signature information is organized as
signature blocks 206 in the manner described herein, the storage system
100 identifies the instances of the data block by reviewing the signature
blocks 206. As described in greater detail above, with reference to FIGS.
2A, 2B, and 3, the signature blocks stored in the client-side signature
repository 121 can include an instances field 210 that identifies the
number of instances of a particular signature 208. Moreover, the
signature block 206 can include location information of the data block in
the location field 218 and access/priority information of the data block
in the access/priority field 220 of each instance of the data block.

[0439] At block 1208, the storage system 100 accesses a data sourcing
policy. The data sourcing policy can be located in one or more components
of the storage system 100. For example, the data sourcing policy can
reside in the storage manager 140, one or more clients 102, the
client-side signature repository 121, one or more media agents 144,
and/or one or more storage devices 108. In some embodiments, portions of
the data sourcing policy reside in different components of the storage
system 100.

[0440] At block 1206, the storage system 100 may have determined that a
particular data block resides in multiple sources within the primary
storage subsystem 117 (e.g., data stores associated with multiple ones of
the clients 102). The data sourcing policy can be used to determine from
which source the data block should be retrieved for the particular
storage operation. For example, during a copy operation when multiple
instances of a data block that is unique to primary storage (i.e., not
located in secondary storage) are located in the primary storage
subsystem, the storage policy can be used to determine which source to
retrieve the data block from for transmission to the secondary storage
subsystem 118. Similarly, during a restore operation, where multiple
copies of a data block reside within the primary storage subsystem 117,
the data sourcing policy can indicate from which source to retrieve the
data block to be restored.

[0441] The data sourcing policy can specify that the determination of the
source of the data block based on a variety of factors. For instance,
characteristics associated with the different sources (e.g.,
characteristics associated with the clients 102 or the primary storage
devices 104), network information, and/or relative priority information
associated with the sources may be used. For example, the data sourcing
policy can compare the relative speeds of the different available
sources, estimated total expected times to retrieve the particular data
block from the available sources, or software or firmware versions
residing on the available sources to determine which source is better
suited to be involved in the storage operation, etc. The data sourcing
policy can also specify that the relative proximity of the available
sources to the target client and/or available network bandwidth between
the available sources and the target client 102B should be factored in to
determine the preferred source. In addition, the data sourcing policy can
specify that if one or more data blocks are to be retrieved from a
particular source client 102, that source client is a preferred source
for subsequent data blocks.

[0442] In some embodiments, the data sourcing policy reviews a priority
indication associated with the sources. The priority indication can
specify the relative priority of a potential data block source (e.g.,
client 102 and/or primary storage device 104) with respect to other
sources. The priority indication can be a fixed value, or can be
determined dynamically, e.g., based on a load associated with the source,
based on the number or types of processes being executed by source, a
user associated with the source, etc. For example, if one source
containing a copy of a data block has a higher priority than another
source, the data sourcing policy can specify that a source with the lower
priority should be used to retrieve the data block. Furthermore, the data
sourcing policy can account for upcoming processes to be performed by the
source. For example, if a source is about to begin a processor intensive
process, the data can be retrieved from a different source. In certain
embodiments, the data sourcing policy selects the source that can most
quickly provide the data block. In general, the sourcing policy can
specify that any combination of the above or other appropriate factors
can be used in making the data block sourcing determination.

[0443] At block 1210, the storage system 100 identifies a preferred source
based on the data sourcing policy. For instance, where the preferred
source is dynamically determined, e.g., on the fly and/or in real time
during a storage operation, once the available sources of the data block
are identified, the accessed data sourcing policy is referred to
determine which of the sources is the preferred source for that
particular storage operation.

[0444] On the other hand, where the preferred source is fixed or otherwise
predetermined, each time a signature block is updated in the client-side
signature repository 121, the storage system 100 can access the sourcing
information (e.g., review the entries of the signature block 206) to
determine the preferred sourcing order for retrieving the data block. In
some cases, different sourcing orders are specified, e.g., depending on
the type storage operation involved and the identity of the target
client.

[0445] The preferred sourcing order can be stored in a separate field of
the signature block, or each entry can include a sourcing rank that
indicates its relative priority among the various potential data block
sources. For instance, in the event, both a top ranked (e.g., high
priority) source and another, lower ranked source maintain a copy of a
data block, the lower ranked source is selected.

[0446] At block 1212, the storage system 100 accesses the data block from
the preferred source. In some embodiments, the source transmits the data
block to the target client 102B (e.g., for a copy operation), the media
agent 144 (e.g., for a restore operation), and/or the client-side
signature repository 121, etc., based on the storage operation.

[0447] One skilled in the art will appreciate that routine 1210 can
include fewer, more, or different blocks than those illustrated in FIG.
12. In some embodiments, the storage system 100 can omit block 1218 and
identify the preferred source without accessing the data block sourcing
policy. For example, if the sources have been previously ranked, the
storage system can identify the preferred source by referring to the
signature block without accessing the data block sourcing policy.

[0448]FIG. 13 is a block diagram illustrative of an expanded view of an
example copy data set index 1302 stored in the storage system 100. The
copy data set index 1302 can be located in one or more components of the
storage system 100. In the illustrated embodiment, the copy data set
index 1302 is located in the secondary storage subsystem 118 within the
media agent 144 and/or the storage device 108.

[0449] Further, the copy data set index 1302 can be generated in response
to a copy operation associated with a client 102. The copy data set index
1302 can include information that can be used by the storage system 100
to identify the signatures of the data blocks involved in the copy
operation and/or determine how the identified data blocks are organized.
The copy data set index 1302 can include information regarding
substantially all of the data stored on a primary storage device(s) 104
associated with a client 102, or of select data (e.g., particular files
or folders or of one or more subclients).

[0450] The copy data set index 1302 can include multiple data entries
1304. While a variety of organizational schemes are possible, in the
illustrated organization, each entry 1304 provides information regarding
the signature of one or more data blocks in a copy data set. For example,
each entry 1304 can include a signature field 1306 and a data block ID
field 1308.

[0451] The signature field 1306 can include a signature of one or more
data blocks that are in the copy data set. The signature can be generated
as described previously with respect to FIGS. 1A-1J, 2A, 2B, and 3. In
some embodiments, each entry 1304 corresponds to a different unique
signature of one or more data blocks that are in the copy data set. For
example, if a particular copy operation involves 1,000 data blocks with a
total of 600 different signatures, the copy data set index 1302 can
include 600 different entries. In certain embodiments, each entry
corresponds to an instance of each data block. For example, with
continued reference to the previous example, the copy data set index 1302
in such a case would include 1,000 entries corresponding to the 1,000
data blocks involved in the storage operation.

[0452] The data block ID field 1308 can include identifiers for each data
block with a signature that matches the signature in the signature field
1306. The identifiers can provide information regarding how the data
blocks are related, such as the order of the data blocks with respect to
one another. For example, the copy data set index 1302 for File A in the
client 102B, can indicate in the data block ID fields 1308 which data
block is first, second, third, and so on, so that when File A is restored
to client 102B, the client 102B will know how the data blocks are to be
arranged. In the illustrated embodiment, Block1, Block3, and Block5 all
have the same signature (Signature1). Similarly, Block4 and Block6 share
Signature3. Block2 has a unique signature. In this embodiment, Block1
corresponds to the first data block of the copy operation, Block2
corresponds to the second data block of the copy operation, etc.
Accordingly, using the copy data set index 1302, the storage system 100
can identify all of the signatures in the copy data set index 1302, all
of the data blocks corresponding to the signature, and the order of the
data blocks with respect to each other.

[0453] The copy data set index 1302 can include additional information as
desired. For example, in some embodiments, the copy data set index 1302
can include signature block reference relating the particular signature
in the copy data set index 1302 with a signature block in the client-side
signature repository 121. In some embodiments, the copy data set index
1302 includes additional metadata (e.g., file and directory metadata).

[0454]FIG. 14 is a flow diagram illustrative of one embodiment of a
routine 1400 implemented by the storage system 100 for executing a
secondary copy operation using a client-slide signature repository 121.
One skilled in the relevant art will appreciate that the elements
outlined for routine 1400 may be implemented by one or more computing
devices/components that are associated with the storage system 100. For
example, the routine 1400 can be implemented by any one, or a combination
of, the storage manager 140, one or more clients 102, the client-side
signature repository 121, one or more media agents 144, and/or one or
more storage devices 108.

[0455] At block 1401, the storage system 100 receives a copy operation
request. For example, the storage manager 140 can instruct the client
102, client-side signature repository 121, and/or media agent 144 to
initiate the copy operation. The request can occur in any of the manners
described herein, such as automatically according to a schedule (e.g.,
daily, weekly, monthly) specified in a storage policy. Alternatively, the
copy operation can occur in response to user interaction with a user
interface. Furthermore, the copy operation request can include
information regarding a specific client whose data is to be copied, the
specific data (e.g., particular files, folders, or portions thereof) that
are to be copied, specific type of operation (e.g., incremental backup,
full backup, snapshot, and the like).

[0456] At block 1402, the storage system 100 identifies a copy data set
associated with the copy operation request.

[0457] In some embodiments, the client-side signature repository 121
includes an index of all the files, folders, etc., found on the clients
102 with which the client-side signature repository 121 is associated.
For example, if the client-side signature repository 121 is associated
with one client it can include an index of all the files, folders, etc.,
found on the one client. If the client-side signature repository 121 is
associated with multiple clients it can include an index of all the
files, folders, etc., found on the multiple clients. The copy data set
index can be used to identify which data blocks correspond to the copy
data set, and how the data blocks are organized. In other cases, such an
index is stored on each client 102.

[0458] At block 1404, the storage system 100 identifies signature blocks
that correspond to the identified data blocks in the copy data set and
that have been modified since a previous copy operation (also referred to
as a modified signature block). A modified signature block can indicate
that an entry has either been added or removed to the signature block
since the previous copy operation, and that a copy of the corresponding
data block has either been added somewhere in primary storage or removed.
Furthermore, a modified signature block can indicate that the secondary
storage does not include references to all of the instances of a
particular data block and/or may not include the data block at all. In
this way, the system can identify which data blocks already exist in
secondary storage and which do not. If the data blocks already exist in
secondary storage, significant time can be saved by during deduplicated
copy operations, by transmitting signature block information as part of a
copy data set index, described below. The signature block information can
indicate that another copy of the data block already exists in the
secondary storage, instead of transmitting the entire data block.

[0459] As mentioned previously, the identification of signature blocks
that have been modified since the previous copy operation can be done by
reviewing the copy operation flag 212 of the signature block. Other
methods can be used to identify signature blocks that have been modified
since the previous copy operation. In some embodiments, the client 102,
the client-side signature repository 121, and/or the media agent 144 can
include an index that maps signatures of data blocks stored in a client
with one or more files or folders stored in the client that have been
previously copied to the secondary storage subsystem. The index can
include how many data blocks are used to form a particular file and how
the data blocks are organized within the file.

[0460] The storage system 100 can also use the age field 222 in the
entries 214 of the signature blocks 206 stored in the client-side
signature repository to identify signature blocks that have been modified
since a previous copy operation. For instance, the storage system 100 can
compare information in the age field, such as creation date or edit date
with date information for a previous copy operation. If the age field
indicates that the entry 214 was added after the previous copy operation,
the storage system 100 can determine that the signature block has been
modified since the previous copy operation.

[0461] For each modified signature block, the storage system 100
determines whether the modified signature block is a new signature block,
as illustrated in decision block 1406. New signature blocks correspond to
signatures and/or corresponding data blocks do not exist in the secondary
storage subsystem 118 and/or signatures that did not exist in the
client-side signature repository 121 prior to the previous backup.
Signature blocks that are not new can correspond to signatures and/or
corresponding data blocks that have been stored in the secondary storage
subsystem 118 in conjunction with a previous copy operation (e.g., as
part of a copy data set index or otherwise) and/or existed in the
client-side signature repository 121 prior to the previous backup. The
system 100 can determine whether the signature block is new in a variety
of ways. For instance, to determine whether the signature block is new,
the system 100 can determine when the signature block was created. If the
signature block was created after a previous copy operation, the
signature block can be identified as new. In some embodiments, if the
signature block contains only one entry, and the one entry is a new
entry, the signature block is identified as new. Furthermore, the system
can refer to a copy operation flag in the signature block that indicates
whether the signature blocks has been part of a copy data set in a copy
operation (e.g., has already been backed up to secondary storage).
Similarly, the system 100 can determine that the signature block is not
new in many different ways. For example, the system can determine that
the signature block is not new when multiple entries are included in the
signature block, when the signature block was created prior to a previous
copy operation that included the corresponding data block, when the copy
operation flag indicates that the signature block has not been part of a
copy operation, or any number of other ways, or any combinations thereof.

[0462] Upon determining that the modified signature block is a new
signature block, the storage system 100 locates the data block
corresponding to the new signature block within the primary storage
subsystem 117 as illustrated in block 1408. The storage system 100 can
also identify the data block corresponding to the signature found in the
signature block as a new data block. In some embodiments, the storage
system locates the data block within the client 102B. In certain
embodiments, the storage system 100 locates the data block within one or
more clients other than client 102B, such as client 102A and 102C.

[0463] Once the data blocks corresponding to the new signature blocks have
been identified, the storage system 100 transmits the located data blocks
and new signature blocks to the secondary storage subsystem 118, as
illustrated in block 1410. In some embodiments the storage system 100
transmits portions of the new signature block but not the entire
signature block. In certain embodiments, the storage system 100 waits
until all modified signature blocks have been reviewed and transmits
multiple located data blocks and multiple new signature blocks to
secondary storage. In some embodiments the storage system 100 transmits
all of the located data blocks and all of the new signature blocks to
secondary storage simultaneously.

[0464] If the storage system 100 determines that the modified signature
block is not a new signature block, the storage system 100 transmits the
modified signature block to the secondary storage subsystem 118, as
illustrated in block 512. By identifying the modified signature block as
not being a new signature block, the storage system 100 has determined
that the corresponding signature that is being reviewed was stored in the
client-side signature repository 121 prior to the previous storage
operation and/or that the corresponding data block exists in the
secondary storage subsystem 118. Accordingly, only the signature block or
portions thereof (e.g., just the signature), and not the data block
itself, are transmitted to secondary storage, so that secondary storage
can update the maps and indices related to the client 102B.

[0465] One skilled in the relevant art will appreciate that routine 1400
can include fewer, more, or different blocks than those illustrated in
FIG. 14. For example, the storage system 100 can transmit a copy data set
index (FIGS. 13-14) to the media agent 144. The copy data set index can
include signature information for all of the data blocks that correspond
to the copy data set. In some embodiments, once the storage system 100
identifies the signature blocks corresponding to the data blocks in the
copy data set and that have been modified since a previous copy
operation, the storage system 100 identifies which of the identified
signature blocks constitute new signature blocks, as described
previously. The storage system 100 then locates and transmits the data
blocks corresponding to the new signature blocks to secondary storage.
The storage system can also transmit the copy data set index to the media
agent, which includes the signature information for all of the data
blocks in the copy data set.

[0466] Further, the retrieved data (data blocks and/or signature blocks)
can be sent from their respective locations either individually or
bundled together. In certain embodiments, a component of the storage
system 100 can bundle all the data blocks and/or signature blocks
together in groups prior to sending the data to secondary storage.
Furthermore, a copy data set index can be generated or retrieved and sent
to secondary storage as well. The copy data set index can indicate how
the various data blocks are related. For example, the copy data set index
can indicate the order of the data blocks with respect to one another
(e.g., for a particular file, group of files, or other copy data set).

[0467] For any of the embodiments described herein, the copies of the data
blocks residing in the primary storage subsystem 117 that are sourced for
generating secondary copy data sets or restore data sets were generated
by programs (e.g., software applications) executing on a client 102
during normal operation. For example, the copies form a portion of a
file, folder, or other type of primary data, and are not cache copies
(e.g., copies made for the purpose of decreasing retrieval time and
removed on a first-in-first-out basis) of other data blocks stored on the
target client 102.

[0468] It will be appreciated by those skilled in the art and others that
all of the functions described in this disclosure may be embodied in
software executed by one or more processors of the disclosed components
and mobile communication devices. The software may be persistently stored
in any type of non-volatile storage.

TERMINOLOGY

[0469] Conditional language, such as, among others, "can," "could,"
"might," or "may," unless specifically stated otherwise, or otherwise
understood within the context as used, is generally intended to convey
that certain embodiments include, while other embodiments do not include,
certain features, elements and/or steps. Thus, such conditional language
is not generally intended to imply that features, elements and/or steps
are in any way required for one or more embodiments or that one or more
embodiments necessarily include logic for deciding, with or without user
input or prompting, whether these features, elements and/or steps are
included or are to be performed in any particular embodiment.

[0470] Depending on the embodiment, certain acts, events, or functions of
any of the algorithms described herein can be performed in a different
sequence, can be added, merged, or left out altogether (e.g., not all
described acts or events are necessary for the practice of the
algorithms). Moreover, in certain embodiments, acts or events can be
performed concurrently, e.g., through multi-threaded processing,
interrupt processing, or multiple processors or processor cores or on
other parallel architectures, rather than sequentially.

[0471] Systems and modules described herein may comprise software,
firmware, hardware, or any combination(s) of software, firmware, or
hardware suitable for the purposes described herein. Software and other
modules may reside on servers, workstations, personal computers,
computerized tablets, PDAs, and other devices suitable for the purposes
described herein. Software and other modules may be accessible via local
memory, via a network, via a browser, or via other means suitable for the
purposes described herein. Data structures described herein may comprise
computer files, variables, programming arrays, programming structures, or
any electronic information storage schemes or methods, or any
combinations thereof, suitable for the purposes described herein. User
interface elements described herein may comprise elements from graphical
user interfaces, command line interfaces, and other suitable interfaces.

[0472] Further, the processing of the various components of the
illustrated systems can be distributed across multiple machines,
networks, and other computing resources. In addition, two or more
components of a system can be combined into fewer components. Various
components of the illustrated systems can be implemented in one or more
virtual machines, rather than in dedicated computer hardware systems.
Likewise, the data repositories shown can represent physical and/or
logical data storage, including, for example, storage area networks or
other distributed storage systems. Moreover, in some embodiments the
connections between the components shown represent possible paths of data
flow, rather than actual connections between hardware. While some
examples of possible connections are shown, any of the subset of the
components shown can communicate with any other subset of components in
various implementations.

[0473] Embodiments are also described above with reference to flow chart
illustrations and/or block diagrams of methods, apparatus (systems) and
computer program products. Each block of the flow chart illustrations
and/or block diagrams, and combinations of blocks in the flow chart
illustrations and/or block diagrams, may be implemented by computer
program instructions. Such instructions may be provided to a processor of
a general purpose computer, special purpose computer, or other
programmable data processing apparatus to produce a machine, such that
the instructions, which execute via the processor of the computer or
other programmable data processing apparatus, create means for
implementing the acts specified in the flow chart and/or block diagram
block or blocks.

[0474] These computer program instructions may also be stored in a
computer-readable memory that can direct a computer or other programmable
data processing apparatus to operate in a particular manner, such that
the instructions stored in the computer-readable memory produce an
article of manufacture including instruction means which implement the
acts specified in the flow chart and/or block diagram block or blocks.
The computer program instructions may also be loaded onto a computer or
other programmable data processing apparatus to cause a series of
operations to be performed on the computer or other programmable
apparatus to produce a computer implemented process such that the
instructions which execute on the computer or other programmable
apparatus provide steps for implementing the acts specified in the flow
chart and/or block diagram block or blocks.

[0475] While certain embodiments have been described, these embodiments
have been presented by way of example only, and are not intended to limit
the scope of the disclosure. Indeed, the novel methods and systems
described herein may be embodied in a variety of other forms;
furthermore, various omissions, substitutions and changes in the form of
the described methods and systems may be made without departing from the
spirit of the disclosure. The accompanying claims and their equivalents
are intended to cover such forms or modifications as would fall within
the scope and spirit of the disclosure.